Definition of extension in English:



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

    ‘the railroad's southern extension’
    • ‘Station improvements are being considered for Shenfield while Gidea Park, Harold Wood and Brentwood are in line for platform extensions and station revamps.’
    • ‘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.’
    • ‘This provides an additional extension of endogenous origin, accommodated by further deformation.’
    • ‘He said he's looking forward to the extension of the 2000 line, which will enable it to handle high-definition television as well.’
    • ‘These courtyards are designed as extensions of the surrounding buildings, serving as outdoor teaching and study rooms.’
    • ‘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.’
    • ‘The extension adds an additional round to the magazine, plus it makes the small Glock more comfortable to shoot.’
    • ‘When these were recommended for refusal, the plans were resubmitted to propose one additional jetty and an extension on the current one.’
    • ‘Part of the growth, clearly, comes from the heavy-hitting brands bringing out new line extensions, hoping to catch the lightning in a bottle.’
    • ‘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.’
    • ‘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.’
    • ‘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.’
    • ‘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.’’
    • ‘But for most people now, their mobile phone is an extension of their arm and they always have it with them.’
    • ‘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.’
    • ‘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.’
    • ‘As in all ophiacodontids, the iliac blade of the Ada Ophiacodon is a straight dorsoposterior extension with no anterior expansion.’
    • ‘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.’
    addition, add-on, adjunct, addendum, augmentation, supplement, appendage, appendix
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    1. 1.1 A room or set of rooms added to an existing building.
      • ‘It is made up of three interconnecting Georgian buildings with a modern extension at the back and has 18 parking spaces.’
      • ‘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.’
      • ‘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.’
      • ‘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.’
      • ‘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.’
      • ‘Their target was the Marine Security Detachment Headquarters, a small extension on the four story main Embassy building.’
      • ‘The building was a meek, red brick building with several extensions to make up for the growth in attendance every year.’
      • ‘While combining the buildings, the extension also expresses historical division.’
      • ‘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…’
      • ‘He redecorated the building and added extensions.’
      • ‘His first task was to design and equip the new museum, part of a planned extension of the main university building.’
      • ‘The first move was to clear the hospital building of ad-hoc extensions, and retrieve the original Blacket structure.’
      • ‘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.’
      • ‘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.’
      • ‘The in-patient Assessment Unit occupies a modern, purpose-built, sympathetic extension to the main 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.’
      addition, add-on, adjunct, addendum, augmentation, supplement, appendage, appendix
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    2. 1.2extensions Lengths of real or artificial hair woven into a person's own hair to create a long hairstyle.
      • ‘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.’
      • ‘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.’
    3. 1.3 The action or process of becoming or making something larger.
      ‘the extension of the President's powers’
      • ‘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.’
      • ‘The basic family unit is universal, as is its extension to create an additional sense of comfort and protection within communities, tribes or nations.’
      • ‘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.’
      • ‘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 linking of environmental requirements to direct payments under EU support and subsidisation schemes was a natural extension of this line of thinking.’
      • ‘The same group of people would miss out on an extension of the telephone allowance.’
      • ‘In addition, the extension of the Dart line to Greystones offers another choice for commuters to the city.’
      expansion, increase, enlargement
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    4. 1.4 An application of an existing system or activity to a new area.
      ‘direct marketing is an extension of telephone selling’
      • ‘The EMEAP working group will proceed to study the extension of the ABF concept to include bonds denominated in regional currencies.’
      • ‘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.’
      • ‘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.’
      • ‘Men 18-34 are more inclined to look beyond buying just a fragrance and aftershave; they're moving on to line extensions.’
      • ‘The principal one, a child of its times, was molecular associationism, a metaphoric extension of the atomism of nineteenth-century physics.’
      • ‘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.’
      • ‘They also avoided medical waste, which was controlled by the mob, a high profit extension to the Family owned hauling firms.’
      • ‘Popular in projections and textbooks, line extensions should however come with a warning: handle with care; this can be hazardous to your bottom line.’
      • ‘As such, offering managed telephony services is a natural extension of their business model.’
      • ‘New apparel, plush and extensions of the toy line are planned.’
      • ‘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.’
      • ‘Consequently, processors have continued their R&D efforts in the kids' yogurt segment, rolling out numerous line extensions in recent months.’
      • ‘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.’
      • ‘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.’
      • ‘By June, nearly 35% of the prescriptions being written were for one of the line extensions, according to Ravera.’
      • ‘The word ‘refer’, in our submission, is the trigger in each of those parts to the extension or additional application of that part.’
      • ‘In the early days of the net, the ITU saw the network as an extension of the international telephone network that it oversees.’
      • ‘Similar commitments by all five of the nuclear powers were essential to gain support for the 1995 extension of the Nuclear Nonproliferation Treaty.’
      expansion, development, progress, advance, advancement, headway, improvement, furtherance, spread, buildout, escalation
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    5. 1.5 An increase in the length of time given to someone to hold office, complete a project, or fulfill an obligation.
      • ‘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.’
      • ‘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.’
      • ‘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.’
      • ‘Because of this conclusion the application fails and the application for extension of time is rejected.’
      • ‘Does that not suggest that we ought to be dealing with an application for extension of time?’
      • ‘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.’
      • ‘This means that 318 individual applications for review and extension would be needed.’
      • ‘There is an application for extension of time which I understand is not opposed.’
      • ‘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.’
      • ‘The opposition Socialist Party argued against an extension, saying emergency measures were no longer needed because violence is abating.’
      • ‘Subject to the outcome of the application for extension of time, there will be a cross-appeal, yes, as I am instructed.’
      • ‘Some of the applications for extension were made before the Court of Appeal decided the matters; some were made after judgment was given.’
      • ‘I will remit this application, including any application for extension of time to the Federal Magistrates Court of Australia.’
      • ‘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.’
      • ‘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.’
      • ‘During the meeting, the board gave the president a two-year contract extension and a raise.’
      • ‘Accordingly the application for extension of time is refused.’
      • ‘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.’
      • ‘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.’
      • ‘Earning the respect of his players after a rocky start three seasons ago, Hartley was given a well-deserved raise and two-year extension.’
      prolongation, lengthening, increase, protraction, continuation, perpetuation
      postponement, deferral, delay
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    6. 1.6Computing An optional suffix to a file name, typically consisting of a period followed by several characters, indicating the file's content or function.
      • ‘Once I have a domain name, I can add aliases and extensions to define additional systems and services.’
      • ‘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.’
      • ‘Most times the extension is the substring which follows the last occurrence, if any, of the dot character.’
  • 2A length of electric cord that permits the use of an appliance at some distance from a fixed socket.

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

    • ‘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.’
    • ‘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.’
    • ‘By this time, Vera had picked up an extension, and was listening in on the conversation, in Charlie's presence.’
    • ‘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.’
    • ‘Prudie finds this issue akin to a spouse or family member listening in on an extension.’
    • ‘Mrs. Jacobs, who had been listening in on an extension, (with Vera's knowledge), offered to drive her to the hospital.’
    1. 3.1 A subsidiary telephone in a set of offices or similar building, on a line leading from the main switchboard but having its own additional number.
      • ‘My door will be knocked down with people looking for line extensions,’ he said.’
      • ‘Lexmark has, however, restored the errant phone extension.’
      • ‘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.’
      • ‘Handsets will be allotted extension numbers in addition to their handphone numbers.’
      • ‘All MSPs need do is pick up the phone, provide their telephone extension, and the cab is on its way.’
      • ‘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.’
      • ‘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.’
      • ‘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.’
      • ‘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.’
      • ‘I listened in on an extension when Frank phoned Jack at Bute House to be told his fate.’
      • ‘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.’
      • ‘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.’
      • ‘McCarthy returned the favor by letting Anderson listen on the extension during supposedly confidential conversations with Republican leaders.’
  • 4The action of moving a limb from a bent to a straight position.

    ‘seizures with sudden rigid extension of the limbs’
    • ‘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.’
    • ‘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 spams are a type of seizure associated with sudden flexion or extension movements.’
    • ‘The patient was distressed on flexion, extension, and internal rotation of the right hip.’
    • ‘Pain is often localised, is worse with extension and rotation, and may be troublesome at night.’
    • ‘No physical evidence of any other movement than knee extension was observed during the stimulations.’
    • ‘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.’
    • ‘Accordingly, the role of vertebral rotation in synapsid locomotion might be better investigated in terms of its effect on limb extension and recovery.’
    • ‘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.’
    • ‘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.’
    • ‘These motions are more complex than simple flexion and extension.’
    • ‘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.’
    • ‘Range of motion, including flexion, extension, lateral rotation and lateral bending, should be assessed.’
    • ‘The extension of the leading arm as already discussed is one of the most significant skills to be mastered.’
    • ‘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.’
    • ‘Hood, a general practitioner, was interested in the movements of flexion and extension, combined with external pressure, used by bone setters for back injuries.’
    • ‘And he was tested at between 10 and 14 degrees of elbow extension during the bowling of the doosra.’
    1. 4.1 The ability of a dancer to raise one leg above their waist, especially to the side.
      ‘she has amazing extension’
      ‘he could perform 180-degree extensions’
      • ‘I have read your advice on extensions and there is one I have a problem with.’
      • ‘Remember that extension is strength and placement as well as flexibility.’
      • ‘So instead of 180 degrees of extension per double push, he'll get 130 or 140, which is more than 90.’
    2. 4.2Medicine The application of traction to a fractured or dislocated limb or to an injured or diseased spinal column to restore it to its normal position.
      • ‘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.’
      • ‘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.’
    3. 4.3 The lengthening of a horse's stride within a particular gait.
      • ‘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 Instruction by a university or college for students who do not attend full time.

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

    Often contrasted with intension
    • ‘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.’
    • ‘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.’
    • ‘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.’
  • 7Philosophy Physics
    The property of occupying space; spatial magnitude.

    ‘nature, for Descartes, was pure extension in space’
    • ‘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.’
    • ‘In particular, he believed that Descartes' identification of matter with extension, and therefore space, entails making it eternal and infinite.’
    • ‘A point is an element that has position, but no extension.’
    • ‘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.’
    • ‘Space was the empty extension that allowed his bits of matter - his atoms - to move about.’


  • by extension

    • Taking the same line of argument further.

      ‘this raised serious questions about his credibility and, by extension, the credibility of the company’
      • ‘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.’
      • ‘And by extension so are his attorneys when it comes to confidential information.’
      • ‘Suddenly the whole future of Woomera - and by extension of the whole remote detention system - is up in the air.’
      • ‘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.’
      • ‘So far the question of asylum seekers and, by extension, racism has been dealt with in a very piecemeal fashion by the Government.’
      • ‘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.’
      • ‘I wonder if, by extension, one could say that radical feminism will soon become a movement that died.’
      • ‘Well, primarily, it has been the Department of Education and, by extension, it has been the Government.’


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