Definition of extension in English:



  • 1A part that is added to something to enlarge or prolong it.

    ‘the railway's southern extension’
    • ‘As in all ophiacodontids, the iliac blade of the Ada Ophiacodon is a straight dorsoposterior extension with no anterior expansion.’
    • ‘I noted the vapor trails that were draped along the leading edge extensions and wingtips as he passed overhead - telltale signs of a high-performance turn.’
    • ‘As the director explains in the program, the musical additions are an extension of the opening line: ‘If music be the food of love, play on.’’
    • ‘He said he's looking forward to the extension of the 2000 line, which will enable it to handle high-definition television as well.’
    • ‘The obvious worry is that the site will come under the control of the prime minister's press spokesman and therefore become little more than an extension of the Party line.’
    • ‘We will use this system as an extension of our network to get to additional buildings and customers and to reach into cities where we don't have significant buildouts.’
    • ‘The MSO must repeat its surveys of housing density use to identify places where the level of growth qualifies for line extensions without the customer contributing to the cost.’
    • ‘It is not officially a branch, but rather an extension of the main line first named the Oshawa Subdivision and re-named the Belleville Subdivision.’
    • ‘But for most people now, their mobile phone is an extension of their arm and they always have it with them.’
    • ‘Part of the growth, clearly, comes from the heavy-hitting brands bringing out new line extensions, hoping to catch the lightning in a bottle.’
    • ‘The extension adds an additional round to the magazine, plus it makes the small Glock more comfortable to shoot.’
    • ‘When he again looked outside during the descent, I had disappeared under his leading-edge extension.’
    • ‘Gables, by the way, are actual extensions of the roof line and are not to be confused with dormer windows, which can spring up in the middle of a section of roof.’
    • ‘When these were recommended for refusal, the plans were resubmitted to propose one additional jetty and an extension on the current one.’
    • ‘The East London line extensions have backing of almost all of London's elected representatives and possess a solid business case approved by the Strategic Rail Authority.’
    • ‘Greig said the proposed M74 extension around the south side of Glasgow would help to take traffic off the M8 but this was still some years away.’
    • ‘These courtyards are designed as extensions of the surrounding buildings, serving as outdoor teaching and study rooms.’
    • ‘Station improvements are being considered for Shenfield while Gidea Park, Harold Wood and Brentwood are in line for platform extensions and station revamps.’
    • ‘This provides an additional extension of endogenous origin, accommodated by further deformation.’
    addition, add-on, adjunct, addendum, augmentation, supplement, appendage, appendix
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    1. 1.1 A room or rooms added to an existing building.
      ‘they hope to demolish the store and build a bar extension’
      • ‘The in-patient Assessment Unit occupies a modern, purpose-built, sympathetic extension to the main building.’
      • ‘While combining the buildings, the extension also expresses historical division.’
      • ‘The first move was to clear the hospital building of ad-hoc extensions, and retrieve the original Blacket structure.’
      • ‘Its plans also include an extension to the main building and a new, separate stable block as well as an upgraded driveway and access to the main road.’
      • ‘The indoor markets in the building extension hereby approved shall be held solely on Saturdays and Sundays and on no other day of the week whatsoever…’
      • ‘The use of the main building and the extension has caused problems to adjacent residents for a number of years and is currently the subject of an ombudsman's complaint against the Council.’
      • ‘With an abundance of space to all sides, the property has potential for the development of a sizeable extension or additional accommodation on its site subject to planning permission.’
      • ‘Their target was the Marine Security Detachment Headquarters, a small extension on the four story main Embassy building.’
      • ‘It is made up of three interconnecting Georgian buildings with a modern extension at the back and has 18 parking spaces.’
      • ‘In Galway, contribution rates for residential units differ depending on location, and people building extensions to private houses don't pay a contribution fee.’
      • ‘She plans to add an additional extension to the front of the house before the builders pack up and leave.’
      • ‘She said the high rates had forced the association to offer its present property for sale as it did not have enough funds to use the land for the building extensions once planned.’
      • ‘His first task was to design and equip the new museum, part of a planned extension of the main university building.’
      • ‘Peter is clearly in a dominant position as his bank is holding itself out as possessing some type of specialist skill, i.e. co-ordinating the planning and building of house extensions.’
      • ‘The free-standing, sky-blue core can be glimpsed as you move through the building and a canted link corridor connects the new extension with the main laboratory.’
      • ‘There will have to be consultation with English Heritage, but the council hopes there will be a glass extension to the building, as a new main entrance from Vernon Street.’
      • ‘The building was a meek, red brick building with several extensions to make up for the growth in attendance every year.’
      • ‘He redecorated the building and added extensions.’
      addition, add-on, adjunct, addendum, augmentation, supplement, appendage, appendix
      View synonyms
    2. 1.2extensions Lengths of artificial hair woven into a person's own hair to create a very long hairstyle.
      • ‘You can have an intricate patterns of different colors or beads added to the extension without additional damage to your hair.’
      • ‘Our real human hair clip on extensions are very easy to use and not noticeable, and it won't damage your own hair.’
      • ‘As the top United Kingdom retailer of clip in hair extension and human hair products, we offer you only the best the industry has to offer.’
    3. 1.3mass noun The action or process of enlarging or extending something.
      ‘the extension of the President's powers’
      • ‘The basic family unit is universal, as is its extension to create an additional sense of comfort and protection within communities, tribes or nations.’
      • ‘In addition, the extension of the Dart line to Greystones offers another choice for commuters to the city.’
      • ‘It was characterised primarily by the fact of extension: it occupied space and was therefore amenable to measurement.’
      • ‘The extension of the canting space at deepwater berths to provide for vessels up to 450 feet long is at present in hand.’
      • ‘The same group of people would miss out on an extension of the telephone allowance.’
      • ‘To a degree this extension of powers was nominal rather than real, for much was a rationalization and codification of hitherto haphazard statute and common law, or a legitimation of what was already police practice.’
      • ‘The linking of environmental requirements to direct payments under EU support and subsidisation schemes was a natural extension of this line of thinking.’
      • ‘The extension to the original building was seamlessly carried out, so it is almost impossible to identify the earlier work.’
      • ‘In amphibians, there is convergent extension of the future neural plate during gastrulation.’
      expansion, increase, enlargement
      View synonyms
    4. 1.4 An application of an existing system or activity to a new area.
      ‘direct marketing is an extension of telephone selling’
      • ‘Men 18-34 are more inclined to look beyond buying just a fragrance and aftershave; they're moving on to line extensions.’
      • ‘As such, offering managed telephony services is a natural extension of their business model.’
      • ‘Demand for cosmetics and toiletries is increasing, as can be seen in the constant introduction of new products and the trend towards brand and line extensions, Euromonitor says.’
      • ‘New apparel, plush and extensions of the toy line are planned.’
      • ‘Saying it's all linguistics is a bit of a strange thing to say, since most of Derrida's work is an extension from work that was itself an extension of Structural Linguistics.’
      • ‘The word ‘refer’, in our submission, is the trigger in each of those parts to the extension or additional application of that part.’
      • ‘Similar commitments by all five of the nuclear powers were essential to gain support for the 1995 extension of the Nuclear Nonproliferation Treaty.’
      • ‘By June, nearly 35% of the prescriptions being written were for one of the line extensions, according to Ravera.’
      • ‘Popular in projections and textbooks, line extensions should however come with a warning: handle with care; this can be hazardous to your bottom line.’
      • ‘Four years later Dirac's positron was also found in a cosmic ray shower and in 1933 Dirac was awarded the Nobel Prize in Physics for his extension of atomic theory.’
      • ‘In the early days of the net, the ITU saw the network as an extension of the international telephone network that it oversees.’
      • ‘Currently the preimplantation selection of embryos is restricted to cases of serious diseases, but the authors urged caution in the future extension of this application.’
      • ‘Consequently, processors have continued their R&D efforts in the kids' yogurt segment, rolling out numerous line extensions in recent months.’
      • ‘Also to come under the umbrella of the project is the town of Kiltimagh which will be provided with additional broadband capacity as an extension of the Ballina scheme.’
      • ‘They also avoided medical waste, which was controlled by the mob, a high profit extension to the Family owned hauling firms.’
      • ‘The EMEAP working group will proceed to study the extension of the ABF concept to include bonds denominated in regional currencies.’
      • ‘At a time when cereal marketing has devolved to price-cutting and me-too line extensions, that's an aggressive marketing push.’
      • ‘Loopy line extensions are not new phenomena; they've just become increasingly dizzying with many often mystifying leaps.’
      • ‘The principal one, a child of its times, was molecular associationism, a metaphoric extension of the atomism of nineteenth-century physics.’
      expansion, development, progress, advance, advancement, headway, improvement, furtherance, spread, buildout, escalation
      View synonyms
    5. 1.5 An additional period of time given to someone to hold office or fulfil an obligation.
      ‘the initial term of appointment is for one year, but an extension of two years is envisaged’
      • ‘Subject to the outcome of the application for extension of time, there will be a cross-appeal, yes, as I am instructed.’
      • ‘Does that not suggest that we ought to be dealing with an application for extension of time?’
      • ‘An alternative construction would be that the late fees were intended to be rental payments for an extension of the term and that the replacement fees were the purchase price of unreturned videos.’
      • ‘Any distribution of any part of the estate made before the application for extension of time shall not be disturbed by reason of that application or any order made thereon.’
      • ‘As I understand it, no one took issue with our lateness, and we did put on an application for extension of time in the second one, as I understand it.’
      • ‘The CEO was able to get out of his lease and into cheaper space, negotiate interest-free extensions on his debt, and significantly reduce operating costs.’
      • ‘This means that 318 individual applications for review and extension would be needed.’
      • ‘Earning the respect of his players after a rocky start three seasons ago, Hartley was given a well-deserved raise and two-year extension.’
      • ‘During the meeting, the board gave the president a two-year contract extension and a raise.’
      • ‘There is an application for extension of time which I understand is not opposed.’
      • ‘Accordingly the application for extension of time is refused.’
      • ‘It is not uncommon on applications for special leave to appeal to have to deal with applications for extension of time, and that can be dealt with then.’
      • ‘We would submit why should it be any different, as long as some evidence is put before the court to the effect that there is a proposed application for extension.’
      • ‘In terms of the long and chequered history of policing in the North, the extension of his term by the Policing Board is of little consequence.’
      • ‘Some of the applications for extension were made before the Court of Appeal decided the matters; some were made after judgment was given.’
      • ‘Because of this conclusion the application fails and the application for extension of time is rejected.’
      • ‘The opposition Socialist Party argued against an extension, saying emergency measures were no longer needed because violence is abating.’
      • ‘I will remit this application, including any application for extension of time to the Federal Magistrates Court of Australia.’
      • ‘As well, I note that the section is discretionary, meaning that even if the criteria are met, the application for extension may be denied for other reasons.’
      • ‘One is the former one of an application for extension of time for service of the summons - I do not apprehend it will be opposed.’
      prolongation, lengthening, increase, protraction, continuation, perpetuation
      postponement, deferral, delay
      View synonyms
    6. 1.6British Permission granted to licensed premises for the sale of alcoholic drinks until later than usual.
      ‘drinks were served until the early hours of the morning, without any extension having been granted’
      • ‘If you wish to have a bar extension, then the catering company will make an application to Crawley Magistrates.’
      • ‘Those residents who wish to oppose any extension to opening times for nearby pubs may now take heart because no extension is possible without planning permission for those hours.’
      • ‘No more than two bar extensions per week are normally granted, of which one is for a Student Society.’
      prolongation, lengthening, increase, protraction, continuation, perpetuation
      View synonyms
    7. 1.7Computing An optional suffix to a filename, typically consisting of a full stop followed by several characters, indicating the file's content or function.
      • ‘Be aware though that there is no standardization to filename extension usage, and many different people have used extensions to apply to many different things.’
      • ‘Once I have a domain name, I can add aliases and extensions to define additional systems and services.’
      • ‘Most times the extension is the substring which follows the last occurrence, if any, of the dot character.’
  • 2A length of electric cable which permits the use of appliances at some distance from a fixed socket.

    • ‘This little extension gives you the ability to plug it in regardless of the USB landscape you are dealing with.’
    • ‘These may be considered either as powercords (if IEC outlets are in use) or as extensions (if used to extend a powercord).’
    • ‘Instead of just having power outputs on one end of an extension cord, designer Wilson Song placed them all along the cord itself.’
    • ‘Floodwaters have caused much damage and several extensions and additional pieces of equipment are urgently needed.’
  • 3A subsidiary telephone on the same line as the main one.

    ‘you can listen on the extension in the bedroom’
    • ‘Prudie finds this issue akin to a spouse or family member listening in on an extension.’
    • ‘With Maddox listening in on the extension, Astor asked Signor Altaverdi if he needed any further copies of the surveillance photographs and told him that he hoped to be back in Italy after the weekend.’
    • ‘This response mode ensured the privacy of adolescents' responses, in the event that parents or siblings were listening to the interview on a telephone extension.’
    • ‘Mrs. Jacobs, who had been listening in on an extension, (with Vera's knowledge), offered to drive her to the hospital.’
    • ‘By this time, Vera had picked up an extension, and was listening in on the conversation, in Charlie's presence.’
    • ‘John Y. Brown, owner of the Buffalo Braves, called Fitz, who had me pick up the extension and listen in.’
    • ‘I wish I didn't have a phone extension in my bedroom, I think lazily.’
    1. 3.1 A subsidiary telephone in a large building, on a line leading from the main switchboard but having its own additional number.
      ‘contact Liz McDonald on extension 3514’
      • ‘Their reasoning is that with an ever-increasing demand to handle new products and line extensions, and given their high failure rate, they feel they need help in dealing with the cash flow and overhead involved.’
      • ‘Look at how many lines and extensions you have at the moment and decide how many your company may require in the future.’
      • ‘Nigel took charge of the cigarette while Pru used the ground-floor extension of the internal telephone system.’
      • ‘My door will be knocked down with people looking for line extensions,’ he said.’
      • ‘Perhaps the Minister could call John Tamihere and tell him that my telephone extension is 6262, so he can communicate to this House just what he thinks of this bill.’
      • ‘Handsets will be allotted extension numbers in addition to their handphone numbers.’
      • ‘I was totally overwhelmed and attempted to cope the best I could, as did the general hospital switchboard, with its extensions all manually connected through an operator in those days.’
      • ‘All MSPs need do is pick up the phone, provide their telephone extension, and the cab is on its way.’
      • ‘For corporations that want extensions and services that are even more closely identified with PBXs uncovered in the corporate globe, this system isn't a very good option.’
      • ‘McCarthy returned the favor by letting Anderson listen on the extension during supposedly confidential conversations with Republican leaders.’
      • ‘Which type of these phone systems you choose will depend on the amount of extensions you require and the features your telephone system needs to have installed.’
      • ‘His place of work is the Resource Library at St. Ann Street Police Station where all other officers have access and he is without a telephone extension.’
      • ‘I listened in on an extension when Frank phoned Jack at Bute House to be told his fate.’
      • ‘Lexmark has, however, restored the errant phone extension.’
      • ‘I would be grateful if you could contact me on the above extension to let me know whether you are coming into the Office or whether you would prefer a home visit.’
  • 4mass noun The action of moving a limb from a bent to a straight position.

    ‘seizures with sudden rigid extension of the limbs’
    • ‘Pain is often localised, is worse with extension and rotation, and may be troublesome at night.’
    • ‘The extension of the leading arm as already discussed is one of the most significant skills to be mastered.’
    • ‘Finally, the provocative test for snapping the iliopsoas tendon is to bring the hip back and forth between flexion and external rotation and extension and internal rotation.’
    • ‘The patient was distressed on flexion, extension, and internal rotation of the right hip.’
    • ‘These motions are more complex than simple flexion and extension.’
    • ‘Hood, a general practitioner, was interested in the movements of flexion and extension, combined with external pressure, used by bone setters for back injuries.’
    • ‘Range of motion, including flexion, extension, lateral rotation and lateral bending, should be assessed.’
    • ‘The straight thrust is a simple, direct extension of the arm used with either a lunge or flèche to touch the opponent.’
    • ‘Standing thoracic and lumbar extension and seated thoracic rotation may be useful therapeutic exercises for patients in the acute and subacute stages of healing.’
    • ‘Muscle bulk, tone and strength were normal, but she displayed decreased range of motion in internal and external rotation, flexion and extension of both shoulders.’
    • ‘And he was tested at between 10 and 14 degrees of elbow extension during the bowling of the doosra.’
    • ‘Accordingly, the role of vertebral rotation in synapsid locomotion might be better investigated in terms of its effect on limb extension and recovery.’
    • ‘The spams are a type of seizure associated with sudden flexion or extension movements.’
    • ‘No physical evidence of any other movement than knee extension was observed during the stimulations.’
    • ‘Muscle endurance testing can be performed with sustained upward gaze, neck extension while in the prone position, and arm abduction against resistance or gravity.’
    • ‘The knee examination is normal, but hip pain is elicited with passive internal rotation or extension of the affected hip.’
    • ‘Normal hip range of motion includes abduction, adduction, circumduction, extension, and flexion.’
    • ‘Sprains and strains may occur with a variety of athletic activities and are more likely to occur with sudden movements involving spinal extension and rotation.’
    • ‘This can be associated with the distal extension of the limb and the formation of digits in an posterior to anterior sequence in most land vertebrates.’
    1. 4.1Ballet The ability of a dancer to raise one leg above their waist, especially to the side.
      ‘she has amazing extension’
      • ‘I have read your advice on extensions and there is one I have a problem with.’
      • ‘So instead of 180 degrees of extension per double push, he'll get 130 or 140, which is more than 90.’
      • ‘Remember that extension is strength and placement as well as flexibility.’
    2. 4.2Medicine The application of traction to a fractured or dislocated limb or to an injured spinal column to restore it to its normal position.
      • ‘Posterior elbow pain in the setting of repetitive elbow extension suggests the diagnosis of triceps tendinosis.’
      • ‘Adolescents with spondylolysis or spondylolisthesis experience an exacerbation of lumbosacral pain with spinal extension.’
      • ‘An evaluation for effusion should be conducted with the patient supine and the injured knee in extension.’
      • ‘The arm is immobilized in a cast with the elbow in extension, and x-rays are obtained.’
      • ‘When the digit has been brought to full extension, a fasciectomy is performed.’
    3. 4.3 The lengthening of a horse's stride at a particular pace.
      • ‘To get that extension where the horse really sits back and goes slowly while making huge strides, the horse is ridden from behind uphill to the extension.’
      • ‘The road horse trot is a fast-stepping trot - characterized by length and rapidity and executed with extreme degree of extension or length of stride.’
  • 5as modifier Denoting instruction by a university or college arranged for people who are not full-time students.

    ‘a postgraduate extension course’
    • ‘She was learning how to crochet, taking a class in it at the extension college.’
    • ‘The lack of opportunities for the higher education of women led to the founding of the university extension movement.’
    • ‘The Food Innovation Center, a branch of Oregon State University's agricultural extension service, is based in Portland.’
    • ‘He went to the University of London (King's College) extension classes and later became an evening class teacher himself.’
    • ‘Rosenow took his concern to Carl Duley, University of Wisconsin county extension agent for Buffalo County.’
    • ‘What was once a small school now serves a wider population that includes adults and extension programs.’
    • ‘We need to adjust our thinking to allow the faculty to provide quality advising, instruction, and extension outreach programs.’
    • ‘Additionally, the International Seminary of Miami is offering some extension courses.’
    • ‘This was in the aftermath of the arrival of proper University extension classes established by the 1902 Education Act.’
    • ‘My wife went to extension classes at the University of North Carolina on post.’
    • ‘Every university should have an extension department to promote students' participation in community-based activities.’
    • ‘Contact Olds College extension services at 1-800-661-6537 for more information.’
    • ‘He also supported London and Oxford in setting up similar extension courses.’
    • ‘In Australia he worked initially as a bush labourer, then as a teacher, and after 1888 for the University of Sydney's extension classes.’
    • ‘Nearby colleges and universities may also offer extension classes.’
    • ‘In fact, there are no universities in Gambia, but in the late 1990s, university extension programs were offered for the first time.’
    • ‘Still barred were the hundreds of students who would have taken courses offered by the university's extension service, mostly English-language classes.’
    • ‘As the school's night college, the extension school attracts extraordinary students.’
    • ‘I checked with every extension office, university, and any other place I could think of; no one could tell me much about it.’
    • ‘Some large nurseries and most university extension services will do this for a nominal charge.’
  • 6Logic
    The range of a term or concept as measured by the objects which it denotes or contains.

    Often contrasted with intension
    • ‘To make sure that the extension of the definiens matches that of the definiendum, Beardsley thinks, the second disjunct of the definition is needed.’
    • ‘All versions of externalism have in common that intensions don't determine extensions.’
    • ‘That is, a concept is indefinitely extensible if any attempt to delineate the extension of the concept leads to an instance of the concept not so delineated.’
    • ‘So the extension of the term ‘marsupial’ is the set of all marsupials: kangaroos, wallabies, wombats, and so on.’
    • ‘Put in modern terms, Abelard holds a theory of direct reference, in which the extension of a term is not a function of its sense.’
  • 7Physics Philosophy
    The property of occupying space.

    ‘nature, for Descartes, was pure extension in space’
    • ‘In particular, he believed that Descartes' identification of matter with extension, and therefore space, entails making it eternal and infinite.’
    • ‘Regardless, physical extension seems nothing more than a relational property as well: the quality of extension in space is not possible without relations amongst constituent parts.’
    • ‘Space was the empty extension that allowed his bits of matter - his atoms - to move about.’
    • ‘This is obvious from our inability to conceive of a half or a third of a soul, or of the extension which a soul occupies.’
    • ‘A point is an element that has position, but no extension.’


  • by extension

    • Taking the same line of argument further.

      ‘the study shows how television and, by extension, the media, alter political relationships’
      • ‘I wonder if, by extension, one could say that radical feminism will soon become a movement that died.’
      • ‘And by extension so are his attorneys when it comes to confidential information.’
      • ‘So far the question of asylum seekers and, by extension, racism has been dealt with in a very piecemeal fashion by the Government.’
      • ‘The drawing itself is often used as an implied symbol of the essential symmetry of the human body, and by extension, to the universe as a whole.’
      • ‘But from past experience, I doubt that any serious combat, and by extension deaths, will occur.’
      • ‘For if both of these apparently carefree images have a message, it is surely of the fleeting nature of such moments and, by extension, of life itself.’
      • ‘Suddenly the whole future of Woomera - and by extension of the whole remote detention system - is up in the air.’
      • ‘Well, primarily, it has been the Department of Education and, by extension, it has been the Government.’
      • ‘Only those who hold ministerial positions in government are accountable to Parliament and by extension the nation.’
      • ‘That would be the boards of directors, and, by extension, the stockholders.’


Late Middle English: from late Latin extensio(n-), from extendere ‘stretch out’ (see extend).