Definition of constant in US English:



  • 1Occurring continuously over a period of time.

    ‘the pain is constant’
    • ‘It will always need constant regeneration, constant effort, and constant activity to continue.’
    • ‘In the longer term, sustained improvements in competitiveness require continuous macroeconomic stability and constant vigilance on the part of individual firms.’
    • ‘Yet still his constant writing and reviewing continued.’
    • ‘They are however symbolic of a constant noise in the background.’
    • ‘Above decks there was constant activity as repairs continued to the newly acquired British ship.’
    • ‘And then the constant repetition and continuous coverage has been astounding.’
    • ‘But his continual torment, his constant wishing to be with the dead, made him certain he could not stand living much longer.’
    • ‘His mother would be unable to continue her constant harping on his bachelor status.’
    • ‘One of the reasons why means are more frequently analysed than ends is because ends are so subjective, contingent, and in constant flux.’
    • ‘Let me tell you about the non-stop insanity, the constant chaos, the perpetual pandemonium.’
    • ‘The two voices behind him had continued in a constant drone since he got on.’
    • ‘There's a constant background hum of machinery, the sound of switches being flicked and the astronauts around you going about their routines.’
    • ‘The constant noise continually startled Gracie and Leah's work.’
    • ‘In clothes stores, sandwich bars, gyms and coffee shops we face a constant barrage of background music - music we notice but rarely listen to.’
    • ‘There's a pirate with a wandering wooden eye who's good for a chuckle, and it's fun to see a pirate tavern where the bar fights are just the constant background noise.’
    • ‘The old fire engines have meant that the staff are subjected to constant breakdowns and are continually looking for spare parts.’
    • ‘The constant spin continues to cancel out the effect of gravity, and keeps the wheel upright.’
    • ‘This season he has been troubled by a groin injury and while receiving constant treatment continues to play.’
    • ‘Many systems survive for decades, undergoing constant tweaking and continual evaluation.’
    • ‘This initiative should be seen as the right way to treat employees, not an opportunity to continue the constant sniping.’
    continual, continuous, persistent, sustained, abiding, round-the-clock
    steadfast, steady, resolute, determined, persevering, tenacious, dogged, unwavering, unflagging, unshaken
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    1. 1.1 Remaining the same over a period of time.
      ‘the company has kept its prices fairly constant’
      • ‘Test-retest reliability examines the temporal stability of a measure or how constant scores remain from one occasion to another.’
      • ‘The actual number of people living in dire poverty has remained roughly constant, at about 1.2 billion.’
      • ‘The number of serious and complicated grievances like infection control issues remained fairly constant throughout the year.’
      • ‘It is important to have a continuous and constant flow rate.’
      • ‘Control bag pH was similar to pH in the lake and remained relatively constant throughout the six-week period.’
      • ‘The reason why different methods can produce widely different results is because a mobile phone does not produce a continuous, constant radiation level.’
      • ‘Although metabolic rate may decline during this period, protein catabolism probably remained rather constant.’
      • ‘Over short periods of time the growth rates remain virtually constant.’
      • ‘Statistics compiled for the Group show that the male suicide rate has more than doubled over the past twenty years while the female rate has remained fairly constant.’
      • ‘So while the share per head of population remains roughly constant, the share for Scotland as a whole is getting smaller.’
      • ‘According to the report, while government aid has remained fairly constant for college students, tuition increases have outstripped the aid.’
      • ‘It was 75 degrees outside but the bedrooms remained at a constant minus 10 degrees somehow.’
      • ‘Consequently, the fructose concentrations remained constant during the feeding period and decreased slowly afterwards.’
      • ‘As previously noted, however, this ratio has remained largely constant for lower-income households as with all others.’
      • ‘However, the 9 percent difference in speed has remained constant over the years.’
      • ‘The expansion of the university sector has meant more degree holders, but the number of jobs has remained roughly constant.’
      • ‘He also noted a rise in pupils staying away from school, although truancy rates remain largely constant.’
      • ‘Only the ratio of the imports of services to total services produced has remained roughly constant during this period.’
      • ‘All definitions remained constant throughout the study period, with the exception of the methodology for counting tests.’
      • ‘However, taste, smell and touch can remain fairly constant well into our seventies and eighties, provided that we don't neglect them.’
      consistent, regular, stable, steady, fixed, uniform, even, level, invariable, unvarying, unchanging, changeless, undeviating, unfluctuating, immutable
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    2. 1.2 (of a person) unchangingly faithful and dependable.
      • ‘He has been my constant companion for over 11 years and a more faithful and devoted one I shall never have.’
      • ‘I even found my old friend steamed broccoli, along with his constant companion, baked chicken without the skin.’
      • ‘They are constant companions - unchanging, unchangeable.’
      • ‘My constant companions were thoroughly entertained.’
      • ‘If your child is ill or you are worried, shout to the rooftops or guilt will walk with you as a constant friend.’
      • ‘Not only would I be leaving my father, I would also be leaving behind my friends, who have been my constant companions since the beginning of my youth.’
      • ‘At that very road crossing, he had said a tearful good-bye to his constant companion and best friend.’
      • ‘They would waltz in and out of my life at intervals and so I theorized that I got ‘used’ to not having any constant friends around.’
      • ‘Improbably, she helps, and stays around to help more, becoming a constant friend.’
      • ‘For the glitterati, pets very often are their most devoted and constant friends and, therefore, enjoy the best money can buy.’
      • ‘It seemed a good idea to begin with the brush because it was the most constant friend.’
      • ‘Having a good, constant friend is important, and being in a prosocial peer group where one is accepted is even better.’
      • ‘Jesus has returned to God and now can be present everywhere for all eternity - so he can be our constant friend.’
      • ‘Those books are my constant friends and if they look a bit tattered and worn, well, so do I.’
      • ‘Apprehension is the constant companion of the true lover.’
      • ‘But it didn't seem to matter as much, because I found a constant friend, Madelyn.’
      • ‘And from a total of 33 constant friends, only half a dozen are ‘bosom buddies’.’
      • ‘Her best friend and constant companion is a gay man, Brent.’
      • ‘I hope you like them, as they'll be your constant friends until you graduate from this class.’
      • ‘The radio was her constant friend and always at her bedside.’
      faithful, loyal, devoted, true, fast, firm, unswerving, unwavering
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  • 1A situation or state of affairs that does not change.

    ‘the condition of struggle remained a constant’
    • ‘There are few constants during a global emergency, but one is that children - the most innocent and vulnerable of all - are among the first to suffer.’
    • ‘They see a hunger for big, high-profile investigations - and the headlines they bring - as the one constant in his case file.’
    • ‘As the international system evolved, some constants remained; notably, this was an era in which states struggled for discrete advantage, not to destroy other states or regimes and not to decide great issues of religion or ideology.’
    • ‘In Chennai, over the years, the amount of road space in a given area has remained a constant.’
    • ‘In any business era, the need to collaborate remains a constant.’
    • ‘The one element that remains a constant through them all is the observation of what a nice man he was.’
    • ‘But the constants remain - Mauao, the beautiful beach and lots of young people.’
    • ‘Girls come and go but the University of Michigan, for example, remains a constant.’
    • ‘The world may be changing, but play remains a constant.’
    • ‘Modes of transport progressed from frontpack to trike to toddling feet as our trio of offspring grew, but the pull-behind grocery cart remained a constant.’
    • ‘While the institution of the secret police evolved to suit the needs of the Soviet state, the capacity for cruelty at the top remained a constant.’
    • ‘But while the genre has certainly had its ups and downs, one thing has also remained a constant: on the whole, they have gotten better.’
    • ‘The story of a young man's alienation from his family, his society or both remains a constant in Canadian cinema.’
    • ‘One characteristic of the Internet that has remained a constant for as long as I have been online is that there is never enough of it.’
    • ‘The theme of loss has remained a constant for nearly 20 years, as has the basic fictional premise of figures in existential free-fall.’
    • ‘What about the death and poverty that will remain a constant in their lives if war, and the regime change that the war will bring about, does not happen?’
    • ‘We have changed our lives in astounding ways since civilization began, and yet commerce has remained a constant.’
    • ‘Soldier technology will continue to increase; however, some constants must remain in our system.’
    • ‘But during the tiny sliver of human history that has seen us attempt to claim the stars as our own, Clarke has remained a bedrock - a constant throughout the struggle.’
    • ‘The story couldn't be convincingly told if there wasn't a convincing constructed context where there are constants, ephemera, characters, events, themes, boundaries, and plot.’
    unchanging factor, unchanging state of affairs, unchanging situation, given
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    1. 1.1Mathematics A quantity or parameter that does not change its value whatever the value of the variables, under a given set of conditions.
      • ‘For a summary of all constants and variables used in the model, see Table 1.’
      • ‘Since its differences are the same as the Fibonacci series differences, we can add or subtract a constant to the Fibonacci series.’
      • ‘By the ‘subject matter of pure mathematics’ he means the ‘continuous quantity’ of geometry and the numerical values of variables and constants in algebra.’
      • ‘His thesis concerned applying the methods of the theory of quadratic number fields to quadratic extensions of a field of rational functions of one variable taken over a finite prime field of constants.’
      • ‘He calculated the constant to 16 decimal places.’
    2. 1.2Physics A number expressing a relation or property which remains the same in all circumstances, or for the same substance under the same conditions.
      • ‘Thus, to interpret the values, some effective temperature must be chosen and this is accomplished by calibrating the force constants to some known property.’
      • ‘The diffraction constant for the diffractometer was calculated using a grating with 0.1 turn spacings.’
      • ‘The importance of the constant is that it measures the strength of the electromagnetic interaction.’
      • ‘One of the great goals of fundamental physics is to find the reason for the precise numerical values of the constants that appear in the equations that prescribe the laws of Nature.’
      • ‘His comedy is a comedy of physics filled with precise formulas for directional qualities, but without standardized parameters or constants.’


Late Middle English (in the sense ‘staying resolute or faithful’): from Old French, from Latin constant- ‘standing firm’, from the verb constare, from con- ‘with’ + stare ‘stand’. The noun senses date from the mid 19th century.