Definition of constant in English:

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Pronunciation: /ˈkɒnst(ə)nt/


1Occurring continuously over a period of time: the constant background noise of the city
More example sentences
  • The constant noise continually startled Gracie and Leah's work.
  • 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.
  • They are however symbolic of a constant noise in the background.
continual, continuous, persistent, sustained, abiding, round-the-clock;
ceaseless, unceasing, perpetual, incessant, never-ending, everlasting, eternal, endless, unending, unabating, non-stop, perennial, unbroken, uninterrupted, unrelieved;
interminable, unremitting, relentless, unrelenting, without respite
literary sempiternal
steadfast, steady, resolute, determined, persevering, tenacious, dogged, unwavering, unflagging, unshaken
1.1Remaining the same over a period of time: these discs rotate at a constant speed
More example sentences
  • However, the 9 percent difference in speed has remained constant over the years.
  • Only the ratio of the imports of services to total services produced has remained roughly constant during this period.
  • Control bag pH was similar to pH in the lake and remained relatively constant throughout the six-week period.
consistent, regular, stable, steady, fixed, uniform, even, level, invariable, unvarying, unchanging, changeless, undeviating, unfluctuating, immutable
1.2(Of a person) unchangingly faithful and dependable: a constant friend
More example sentences
  • Her best friend and constant companion is a gay man, Brent.
  • At that very road crossing, he had said a tearful good-bye to his constant companion and best friend.
  • They are constant companions - unchanging, unchangeable.
faithful, loyal, devoted, true, fast, firm, unswerving, unwavering;
steadfast, staunch, stalwart, dependable, trustworthy, trusty, reliable, dedicated, committed;
bosom, boon


1A situation that does not change: the condition of struggle remained a constant
More example sentences
  • 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.
  • But the constants remain - Mauao, the beautiful beach and lots of young people.
  • 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.
unchanging factor, unchanging state of affairs, unchanging situation, given
1.1 Mathematics A quantity or parameter that does not change its value whatever the value of the variables, under a given set of conditions.
Example sentences
  • By the ‘subject matter of pure mathematics’ he means the ‘continuous quantity’ of geometry and the numerical values of variables and constants in algebra.
  • Since its differences are the same as the Fibonacci series differences, we can add or subtract a constant to the Fibonacci series.
  • He calculated the constant to 16 decimal places.
1.2 Physics A number expressing a relation or property which remains the same in all circumstances, or for the same substance under the same conditions.
Example sentences
  • The diffraction constant for the diffractometer was calculated using a grating with 0.1 turn spacings.
  • 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 importance of the constant is that it measures the strength of the electromagnetic interaction.


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.

For editors and proofreaders

Line breaks: con|stant

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