constant

1 of 2

adjective

con·​stant ˈkän(t)-stənt 

1

: marked by firm steadfast resolution or faithfulness : exhibiting constancy of mind or attachment

a constant friend

2

: invariable, uniform

a constant flow

should be stored at a constant temperature

3

: continually occurring or recurring : regular

a constant annoyance

suffers from constant headaches

constant

2 of 2

noun

: something invariable or unchanging: such as

a

: a number that has a fixed value in a given situation or universally or that is characteristic of some substance or instrument

b

: a number that is assumed not to change value in a given mathematical discussion

c

: a term in logic with a fixed designation

d

: something or someone that is reliably present or available

My parents put in me in piano lessons when I was really young, so music has always been a constant in my life.

—Mélat

He's my constant for when I seek guidance both on a professional and personal front.

—Gautam Mehra

Synonyms

Adjective

• steady
• unchanging
• stable

Choose the Right Synonym for constant

faithful, loyal, constant, staunch, steadfast, resolute mean firm in adherence to whatever one owes allegiance.

faithful implies unswerving adherence to a person or thing or to the oath or promise by which a tie was contracted.

faithful to her promise

loyal implies a firm resistance to any temptation to desert or betray.

remained loyal to the czar

constant stresses continuing firmness of emotional attachment without necessarily implying strict obedience to promises or vows.

constant friends

staunch suggests fortitude and resolution in adherence and imperviousness to influences that would weaken it.

a staunch defender of free speech

steadfast implies a steady and unwavering course in love, allegiance, or conviction.

steadfast in their support

resolute implies firm determination to adhere to a cause or purpose.

a resolute ally

continual, continuous, constant, incessant, perpetual, perennial mean characterized by continued occurrence or recurrence.

continual often implies a close prolonged succession or recurrence.

continual showers the whole weekend

continuous usually implies an uninterrupted flow or spatial extension.

football's oldest continuous rivalry

constant implies uniform or persistent occurrence or recurrence.

lived in constant pain

incessant implies ceaseless or uninterrupted activity.

annoyed by the incessant quarreling

perpetual suggests unfailing repetition or lasting duration.

a land of perpetual snowfall

perennial implies enduring existence often through constant renewal.

a perennial source of controversy

Examples of constant in a Sentence

Adjective

He suffers from constant headaches.

Her constant chatter was a nuisance.

The house is in constant need of repairs.

The scar serves as a constant reminder of the accident.

a problem demanding constant attention

The equipment should be stored at a constant temperature.

He kept the car's speed constant.

She has struggled to maintain a constant weight.

They remained constant friends throughout their lives.

Noun

Her job was the one constant in her life.

Recent Examples on the Web

Adjective

Ukraine needs a constant pipeline of weapons from its allies to defend against Russian barrages of missiles and drones – often several hundred in one night. —Laura Sharman, CNN Money, 26 Oct. 2025

Michael Kayode’s cannonball long throws, which Slot said Liverpool had practised defending on Friday and spoken about again on Saturday, were a constant problem, but the visitors repeatedly, and needlessly, aided Brentford by putting the ball out of play in their own defensive third. —Tim Spiers, New York Times, 26 Oct. 2025

Noun

According to Thorsten Schumm, PhD, a researcher at the Vienna University of Technology’s (TU Wien) Institute of Atomic and Subatomic Physics, some theories suggest that the fine-structure constant may not be truly constant. —Georgina Jedikovska, Interesting Engineering, 27 Oct. 2025

Both of the major sets of teams were wrong; the true value of the Hubble constant was actually in between the two. —Big Think, 17 Oct. 2025

Word History

Etymology

Adjective and Noun

Middle English, from Middle French, from Latin constant-, constans, from present participle of constare to stand firm, be consistent, from com- + stare to stand — more at stand

First Known Use

Adjective

14th century, in the meaning defined at sense 1

Noun

1832, in the meaning defined above

Phrases Containing constant

• Boltzmann constant
• Boltzmann's constant
• constant companion
• cosmological constant
• dielectric constant
• equilibrium constant
• Michaelis constant
• Planck constant
• Planck's constant
• solar constant

Rhymes for constant

• inconstant

Kids Definition

constant

1 of 2 adjective

con·​stant ˈkän(t)-stənt 

1

: always faithful and true

constant friends

2

: remaining steady and unchanged

a constant temperature

3

: occurring over and over again

constant headaches

constantly adverb

constant

2 of 2 noun

: something unchanging

especially : a quantity whose value does not change under given mathematical conditions compare variable sense 1

Medical Definition

constant

1 of 2 adjective

con·​stant ˈkän(t)-stənt 

: remaining unchanged

constantly adverb

constant

2 of 2 noun

: something invariable or unchanging

especially : a number that has a fixed value in a given situation or universally or that is characteristic of some substance or instrument