certain

American  

[sur-tn] / ˈsɜr tn /

adjective

1. free from doubt or reservation; confident; sure.

   I am certain he will come.

   Synonyms:

   satisfied

2. destined; sure to happen (usually followed by an infinitive).

   He is certain to be there.

3. inevitable; bound to come.

   They realized then that war was certain.

4. established as true or sure; unquestionable; indisputable.

   It is certain that he tried.

   Synonyms:

   clear, plain, obvious, incontrovertible, irrefutable, incontestable, indubitable

5. fixed; agreed upon; settled.

   on a certain day; for a certain amount.

   Synonyms:

   determined

6. definite or particular, but not named or specified.

   A certain person phoned. He had a certain charm.

7. that may be depended on; trustworthy; unfailing; reliable.

   His aim was certain.

8. some though not much.

   a certain reluctance.

9. Obsolete. steadfast.

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pronoun

1. certain ones.

   Certain of the members declined the invitation.

idioms

1. for certain, without a doubt; surely.

   I know for certain that I have seen that face before.

certain British  

/ ˈsɜːtən /

adjective

1. (postpositive) positive and confident about the truth of something; convinced

   I am certain that he wrote a book

2. (usually postpositive) definitely known

   it is certain that they were on the bus

3. (usually postpositive) sure; bound; destined

   he was certain to fail

4. decided or settled upon; fixed

   the date is already certain for the invasion

5. unfailing; reliable

   his judgment is certain

6. moderate or minimum

   to a certain extent

7. to ensure (that one will get something); confirm

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adverb

1. definitely; without a doubt

   he will win for certain

determiner

1. 1. known but not specified or named

      certain people may doubt this

   2. ( as pronoun; functioning as plural )

      certain of the members have not paid their subscriptions

2. named but not known

   he had written to a certain Mrs Smith

certain More Idioms  

1. see for certain.

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Usage

What are other ways to say certain? Someone who is certain of something is free from doubt or reservation about it. How is certain different from sure, confident, and positive? Find out on Thesaurus.com.

Etymology

Origin of certain

First recorded in 1250–1300; Middle English, from Old French, from Vulgar Latin certānus (unrecorded), from Latin cert(us) “sure, settled” (adjective use of past participle of cernere “to decide, separate, sift”) + -ānus -an

Example Sentences

"There's certain situations where pride holds you back - but sometimes you have to just shed that pride and go for it."

From BBC • Apr. 2, 2026

The FDA won’t enforce certain provisions of the Federal Food, Drug, and Cosmetic Act for hemp-derived oral products solely because they contain CBD, Commissioner Marty Makary said in a letter Wednesday.

From Barron's • Apr. 2, 2026

After Congress passed a law forcing their release, Bondi presided over that release — amid criticisms she was slow-walking it, withholding certain records and overly redacting others.

From Los Angeles Times • Apr. 2, 2026

The property’s status is currently listed as “contingent,” meaning that the deal is being readied for closing, but that certain conditions need to be met before a sale can be finalized.

From MarketWatch • Apr. 2, 2026

She would not know, for certain, which realm had met him with an open door.

From "The Undead Fox of Deadwood Forest" by Aubrey Hartman

Related Words

• absolute
• clear
• definite
• genuine
• positive
• real
• safe
• sure
• true
• undeniable