certain

1 of 2

adjective

cer·​tain ˈsər-tᵊn 

1

: fixed, settled

a certain percentage of the profit

2

: of a specific but unspecified character, quantity, or degree

the house has a certain charm

3

a

: dependable, reliable

a certain remedy for the disease

b

: known or proved to be true : indisputable

it is certain that we exist

4

a

: inevitable

the certain advance of age

b

: incapable of failing : destined

—used with a following infinitive

she is certain to do well

5

: assured in mind or action

I am certain they are right

certain

2 of 2

pronoun

plural in construction

: certain ones

certain of my generation

—W. B. Yeats

Phrases

for certain

: as a certainty : assuredly

the cause is not known for certain

of a certain age

: of a somewhat advanced age : no longer young

remembered by people of a certain age

Synonyms

Adjective

• anonymous
• given
• one
• some
• unidentified
• unnamed
• unspecified

Choose the Right Synonym for certain

sure, certain, positive, cocksure mean having no doubt or uncertainty.

sure usually stresses the subjective or intuitive feeling of assurance.

felt sure that I had forgotten something

certain may apply to a basing of a conclusion or conviction on definite grounds or indubitable evidence.

police are certain about the cause of the fire

positive intensifies sureness or certainty and may imply opinionated conviction or forceful expression of it.

I'm positive that's the person I saw

cocksure implies presumptuous or careless positiveness.

you're always so cocksure about everything

Examples of certain in a Sentence

Adjective

I'm fairly certain that I'll be on time.

a certain person told me that today is your birthday

Recent Examples on the Web

Adjective

What is Valley fever? Valley fever is a lung infection caused by breathing in spores from Coccidioides, a fungus that lives in the soil and dust in certain regions of the United States and the world, according to the Centers for Disease Control and Prevention (CDC). —Terry Collins, USA Today, 17 May 2025

However, while certain trends like being compliant with privacy regulations are a must to follow, the choice of others should depend on your goals and target audience. —Roman Vrublivskyi, Forbes.com, 16 May 2025

This introduction to a group of 12- and 13-year-old boys as faceless forces of nature will prove apt in certain ways, although Polinger is careful not to make any of them one-dimensional. —Sophie Monks Kaufman, IndieWire, 16 May 2025

These fears can lead to excessive cleaning, handwashing, or avoidance of certain places, people, or objects.5 People with contamination OCD may also experience intense feelings of disgust when touching certain things. —Health, 16 May 2025

Word History

Etymology

Adjective

Middle English certeyn, certayne, borrowed from Anglo-French certein, certain, going back to Vulgar Latin *certānus, from Latin certus "fixed, settled, indisputable," originally past participle of cernere "to sift, discern, decide, determine" (going back to an Indo-European present stem *kri-n-, verbal adjective *kri-to-, from a verbal base *krei̯̯̯(h₁)- "sift, separate," whence Greek krī́nein "to separate, choose, decide," verbal adjective kritós, Welsh gogrynu "to sift") + -ānus + -an entry 2

Pronoun

Middle English certyn, derivative of certeyn certain entry 1

First Known Use

Adjective

13th century, in the meaning defined at sense 1

Pronoun

15th century, in the meaning defined above

Phrases Containing certain

• a certain
• all but certain to
• make certain
• make certain of
• to a certain extent
• under certain circumstances

Rhymes for certain

• bertin
• curtain
• uncertain

Kids Definition

certain

1 of 2 adjective

cer·​tain ˈsərt-ᵊn 

1

: fixed sense 1b

receive a certain share of the profits

2

: not to be doubted : known to be true

it is certain that diamonds are hard

3

: known but not named

a certain person told me

4

: reliable, sure

a certain cure

5

a

: sure to happen : bound to occur : inevitable

defeat was certain

b

: decided in advance by or as if by fate

the plan was certain to succeed

6

: assured in mind or action

feel certain they will come

certain

2 of 2 pronoun

: certain ones

certain of them attended