See more synonyms for constant on
  1. not changing or varying; uniform; regular; invariable: All conditions during the three experiments were constant.
  2. continuing without pause or letup; unceasing: constant noise.
  3. regularly recurrent; continual; persistent: He found it impossible to work with constant interruption.
  4. faithful; unswerving in love, devotion, etc.: a constant lover.
  5. steadfast; firm in mind or purpose; resolute.
  6. Obsolete. certain; confident.
  1. something that does not or cannot change or vary.
  2. Physics. a number expressing a property, quantity, or relation that remains unchanged under specified conditions.
  3. Mathematics. a quantity assumed to be unchanged throughout a given discussion.

Origin of constant

1350–1400; Middle English < Latin constant- (stem of constāns, present participle of constāre to stand firm), equivalent to con- con- + stā- stand + -nt- present participle suffix
Related formscon·stant·ly, adverbnon·con·stant, noun, adjectiveo·ver·con·stant, adjectiveo·ver·con·stant·ly, adverbo·ver·con·stant·ness, nounqua·si-con·stant, adjectivequa·si-con·stant·ly, adverbun·con·stant, adjectiveun·con·stant·ly, adverb

Synonyms for constant

See more synonyms for on
1. unchanging, immutable, permanent. 2. perpetual, unremitting, uninterrupted. 3. incessant, ceaseless. 4. loyal, staunch, true. See faithful. 5. steady, unwavering, unswerving.

Antonyms for constant

1. changeable. 2. fitful. 3. sporadic. 4. unreliable. 5. wavering.


  1. Paul Hen·ri Ben·ja·min Bal·luat [pawl ahn-ree ban-zha-man ba-lwa] /pɔl ɑ̃ˈri bɛ̃ ʒaˈmɛ̃ baˈlwa/. Paul d'Estournelles de Constant.
  2. Jean Jo·seph Ben·ja·min [zhahn zhaw-zef ban-zha-man] /ʒɑ̃ ʒɔˈzɛf bɛ̃ ʒaˈmɛ̃/, 1845–1902, French painter. Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for constant

Contemporary Examples of constant

Historical Examples of constant

British Dictionary definitions for constant


  1. fixed and invariable; unchanging
  2. continual or continuous; incessantconstant interruptions
  3. resolute in mind, purpose, or affection; loyal
  1. something that is permanent or unchanging
  2. a specific quantity that is always invariablethe velocity of light is a constant
    1. mathsa symbol representing an unspecified number that remains invariable throughout a particular series of operations
    2. physicsa theoretical or experimental quantity or property that is considered invariable throughout a particular series of calculations or experiments
  3. See logical constant
Derived Formsconstantly, adverb

Word Origin for constant

C14: from Old French, from Latin constāns standing firm, from constāre to be steadfast, from stāre to stand


  1. Benjamin (bɛ̃ʒamɛ̃). real name Henri Benjamin Constant de Rebecque. 1767–1830, French writer and politician: author of the psychological novel Adolphe (1816)
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for constant

late 14c., "steadfast, resolute," from Old French constant (14c.) or directly from Latin constantem (nominative constans) "standing firm, stable, steadfast, faithful," present participle of constare, from com- "together" (see com-) + stare "to stand," from PIE root *sta- "to stand" (see stet). Of actions and conditions from 1650s. Related: Constantly.


1832 in mathematics and physics, from constant (adj.).

Online Etymology Dictionary, © 2010 Douglas Harper

constant in Medicine


  1. Continually occurring; persistent.
  2. Unchanging in nature, value, or extent; invariable.
  1. A quantity assumed to have a fixed value in a specified mathematical context.
  2. An experimental or theoretical condition, factor, or quantity that does not vary or that is regarded as invariant in specified circumstances.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

constant in Science


  1. A quantity that is unknown but assumed to have a fixed value in a specified mathematical context.
  2. A theoretical or experimental quantity, condition, or factor that does not vary in specified circumstances. Avogadro's number and Planck's constant are examples of constants.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

constant in Culture


A number that appears in equations and formulas and does not vary or change. Examples are Planck's constant and the speed of light.

The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.