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• constant
  constant

  adjective

  not changing or varying; uniform; regular; invariable.
• Constant
  Constant

  noun

  Paul Henri Benjamin Balluat Paul d'Estournelles de Constant.

constant

¹ American  

[kon-stuhnt] / ˈkɒn stənt /

adjective

1. not changing or varying; uniform; regular; invariable.

   All conditions during the three experiments were constant.

   Synonyms:

   permanent, immutable

   Antonyms:

   changeable

2. continuing without pause or letup; unceasing.

   constant noise.

   Synonyms:

   unremitting, perpetual

   Antonyms:

   fitful

3. regularly recurrent; continual; persistent.

   He found it impossible to work with constant interruption.

   Synonyms:

   ceaseless, incessant

   Antonyms:

   sporadic

4. faithful; unswerving in love, devotion, etc..

   a constant lover.

   Synonyms:

   true, staunch, loyal

   Antonyms:

   unreliable

5. steadfast; firm in mind or purpose; resolute.

   Synonyms:

   steady

6. Obsolete. certain; confident.

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noun

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.

Constant ² American  

[kawn-stahn] / kɔ̃ˈstɑ̃ /

noun

1. Paul Henri Benjamin Balluat Paul d'Estournelles de Constant.

2. Jean Joseph Benjamin 1845–1902, French painter.

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Constant ¹ British  

/ kɔ̃stɑ̃ /

noun

1. Benjamin (bɛ̃ʒamɛ̃). real name Henri Benjamin Constant de Rebecque. 1767–1830, French writer and politician: author of the psychological novel Adolphe (1816)

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constant ² British  

/ ˈkɒnstənt /

adjective

1. fixed and invariable; unchanging

2. continual or continuous; incessant

   constant interruptions

3. resolute in mind, purpose, or affection; loyal

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noun

1. something that is permanent or unchanging

2. a specific quantity that is always invariable

   the velocity of light is a constant

3. 1. maths a symbol representing an unspecified number that remains invariable throughout a particular series of operations

   2. physics a theoretical or experimental quantity or property that is considered invariable throughout a particular series of calculations or experiments

4. See logical constant

constant Scientific  

/ kŏn′stənt /

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.

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constant Cultural  

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

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Related Words

See faithful.

Other Word Forms

• constantly
  adverb
• nonconstant
  noun
• overconstant
  adjective
• overconstantness
  noun
• quasi-constant
  adjective
• unconstant
  adjective

Etymology

Origin of constant

First recorded in 1350–1400; Middle English, from Latin constant- (stem of constāns, present participle of constāre “to stand firm”), equivalent to con- con- + stā- stand + -nt- present participle suffix

Explanation

Think of something or someone that does not change as constant. A classmate's constant drumming on the table with his fingers could be a constant source of annoyance. Constant derives from Latin verb meaning "to stand with," so something constant is continually standing with you and not wavering. You may be thankful for the constant companionship of your dog but not necessarily for your teacher's constant homework assignments. In math and science, a constant is a number that is fixed and known, unlike a variable which changes with the context. That idea crosses over to real life. If a friend is a constant in your life, that means they have always been with you and there for you.

Example Sentences

There are very few land areas, only a small number of weather stations, and nearly constant cloud cover.

From Science Daily • May 14, 2026

However, during engine operation, moving parts such as pistons require constant lubrication, making it unavoidable that small amounts of engine oil enter the combustion chamber.

From Science Daily • May 13, 2026

Around 100 of its former staff have joined the army and recruitment is a constant struggle.

From Barron's • May 13, 2026

Orbiting satellites with solar panels on the dusk/dawn line have constant sunlight.

From The Wall Street Journal • May 12, 2026

I know I don’t need more than I already have, but my sweater from the Ranch is starting to pill, and the constant washing in the sink has been annoying.

From "The Wrong Way Home" by Kate O’Shaughnessy

Related Words

• ceaseless
• chronic
• continual
• continuous
• endless
• eternal
• incessant
• nonstop
• perpetual
• persistent
• relentless
• sustained
• unending
• uninterrupted
• unrelenting
• unremitting