• synonyms


See more synonyms for certain on Thesaurus.com
  1. free from doubt or reservation; confident; sure: I am certain he will come.
  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.
  5. fixed; agreed upon; settled: on a certain day; for a certain amount.
  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.
Show More
  1. certain ones: Certain of the members declined the invitation.
Show More
  1. for certain, without a doubt; surely: I know for certain that I have seen that face before.
Show More

Origin of certain

1250–1300; Middle English < Old French < Vulgar Latin *certānus, equivalent to Latin cert(us) sure, settled (cer- base of cernere to decide, + -tus past participle suffix) + -ānus -an

Synonyms for certain

See more synonyms for on Thesaurus.com
1. convinced, satisfied. See sure. 4. indubitable, incontestable, irrefutable, incontrovertible, obvious, plain, clear. 5. determined.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Related Words for certain

positive, sure, convinced, real, genuine, undeniable, clear, safe, definite, absolute, true, precise, specified, specific, individual, various, particular, numerous, special, assertive

Examples from the Web for certain

Contemporary Examples of certain

Historical Examples of certain

  • After all, there are certain things that you can't tell in too few words.

    The Spenders

    Harry Leon Wilson

  • Youth is prone to endow its opinions with all the dignity of certain knowledge.

    The Spenders

    Harry Leon Wilson

  • Certain faculties develop in response to the pressure of environment.

    The Spenders

    Harry Leon Wilson

  • But its prisoners were not exempt from its heat, like certain holy ones of old.

    The Spenders

    Harry Leon Wilson

  • So certain was he as to the exact locality, that he offered to conduct a party to the place.

British Dictionary definitions for certain


  1. (postpositive) positive and confident about the truth of something; convincedI am certain that he wrote a book
  2. (usually postpositive) definitely knownit is certain that they were on the bus
  3. (usually postpositive) sure; bound; destinedhe was certain to fail
  4. decided or settled upon; fixedthe date is already certain for the invasion
  5. unfailing; reliablehis judgment is certain
  6. moderate or minimumto a certain extent
  7. make certain of to ensure (that one will get something); confirm
Show More
  1. for certain definitely; without a doubthe will win for certain
Show More
    1. known but not specified or namedcertain people may doubt this
    2. (as pronoun; functioning as plural)certain of the members have not paid their subscriptions
  1. named but not knownhe had written to a certain Mrs Smith
Show More

Word Origin for certain

C13: from Old French, from Latin certus sure, fixed, from cernere to discern, decide
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for certain


c.1300, "determined, fixed," from Old French certain "reliable, sure, assured" (12c.), from Vulgar Latin *certanus, from Latin certus "sure, fixed, settled, determined" (also source of Italian certo, Spanish cierto), originally a variant past participle of cernere "to distinguish, decide," literally "to sift, separate" (see crisis).

Of persons, "full of confidence in one's knowledge or judgment," from mid-14c. Euphemistic use (of a certain age, etc.) attested from mid-18c. Certainer, certainest were common to c.1750, but have fallen from proper use for some reason. Expression for certain "assuredly" is attested by early 14c.

Show More
Online Etymology Dictionary, © 2010 Douglas Harper

Idioms and Phrases with certain


see for certain.

Show More
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.