certain

[sur-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.

pronoun

1. certain ones.

   Certain of the members declined the invitation.

certain

/ 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

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

Word History and Origins

Origin of certain¹

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

Word History and Origins

Origin of certain¹

C13: from Old French, from Latin certus sure, fixed, from cernere to discern, decide

Idioms and Phrases

Idioms

1. for certain, without a doubt; surely.

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

see for certain.

Example Sentences

AI-enabled robots might one day be programmed to work on cars, but Hannah says mechanics develop a feel for the vibrations and sounds associated with certain problems—something a robot couldn’t do.

Read more on The Wall Street Journal

I was certain it would be the right decision in the long run, especially if one or both of us became ill or disabled.

Read more on The Wall Street Journal

Staying with family not only eliminates lodging fees, but cuts down on certain “fringe” costs.

Read more on MarketWatch

Da Silva’s victory is far from certain, with public anger bubbling over crime.

Read more on The Wall Street Journal

However, this classic explanation does not account for certain volcanic behavior.

Read more on Science Daily

Related Words

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

When To Use

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.