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. make certain of
   to ensure (that one will get something); confirm

adverb

1. for certain
   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.

More idioms and phrases containing certain

see for certain .

Example Sentences

Additionally, ancient adaptation signals can be masked by genetic drift -- random fluctuations in the frequency that genes appear -- and population mixing, which causes certain adaptive traits to disappear from the gene pool.

From Science Daily

Such artificial proteins are designed to bind to certain viruses or transport drugs, for example.

From Science Daily

Talent, of course, is one of the main reasons certain actors make such convincing villains.

From Los Angeles Times

The department has long faced allegations about secretive deputy groups running amok in certain stations and jails, controlling command staff and promoting a culture of violence.

From Los Angeles Times

Peaches need "peach chill" — a certain amount of time in temperatures that are under 45 degrees Fahrenheit.

From Salon

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.