from The American Heritage® Dictionary of the English Language, 5th Edition.

  • adjective Definite; fixed.
  • adjective Sure to come or happen; inevitable.
  • adjective Established beyond doubt or question; indisputable.
  • adjective Capable of being relied on; dependable.
  • adjective Having or showing confidence; assured.
  • adjective Not specified or identified but assumed to be known.
  • adjective Named but not known or previously mentioned.
  • adjective Perceptible; noticeable.
  • adjective Not great; calculable.
  • pronoun An indefinite but limited number; some.
  • idiom (for certain) Without doubt; definitely.

from The Century Dictionary.

  • Certainly; assuredly.
  • Fixed; determinate; definite; specified; prescribed; settled beforehand: as in the phrase “at a time certain.
  • Indefinite in the sense of not being specifically named; known but not described: applied to one or more real individual objects or characters, as distinguished from a class of objects or an order of characters; coming under particular observation, but undefined, as to kind, number, quantity, duration, etc.; some particular: as, a lady of a certain age.
  • Some (known but unspecified): followed by of.
  • Established as true or sure; placed beyond doubt; positively ascertained and known; unquestionable; indisputable.
  • Capable of being depended on; trustworthy.
  • Unfailing; unerring; sure; positive: as, a certain remedy for rheumatism.
  • Assured; free from doubt regarding: used absolutely, or with of, and formerly sometimes with on.
  • Sure: with an infinitive: as, he is certain to be there to-morrow.
  • Synonyms Undeniable, unquestionable, undoubted, indubitable, indisputable, incontrovertible, inevitable. Sure, Positive, Certain, Confident, etc. (see confident); unhesitating, undoubting.
  • noun A definite but unstated quantity.
  • noun Certainty.
  • noun In the Roman Catholic Church, prayers said daily at mass for specified persons, as for the members of a guild unable to keep a priest of its own, but who paid so much to a church to have a daily remembrance. Also certainty.

from the GNU version of the Collaborative International Dictionary of English.

  • adverb obsolete Certainly.
  • noun obsolete Certainty.
  • noun obsolete A certain number or quantity.
  • adjective Assured in mind; having no doubts; free from suspicions concerning.
  • adjective Determined; resolved; -- used with an infinitive.
  • adjective Not to be doubted or denied; established as a fact.
  • adjective Actually existing; sure to happen; inevitable.
  • adjective Unfailing; infallible.
  • adjective Fixed or stated; regular; determinate.
  • adjective Not specifically named; indeterminate; indefinite; one or some; -- sometimes used independenty as a noun, and meaning certain persons.
  • adjective assuredly.
  • adjective certainly.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

  • adjective Sure, positive, not doubting.
  • determiner Having been determined but unspecified. The quality of some particular subject or object which is known by the speaker to have been specifically singled out among similar entities of its class.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • adjective exercising or taking care great enough to bring assurance
  • adjective reliable in operation or effect
  • adjective having or feeling no doubt or uncertainty; confident and assured
  • adjective certain to occur; destined or inevitable
  • adjective definite but not specified or identified
  • adjective established beyond doubt or question; definitely known
  • adjective established irrevocably


from The American Heritage® Dictionary of the English Language, 4th Edition

[Middle English, from Old French, from Vulgar Latin *certānus, from Latin certus, past participle of cernere, to determine; see krei- in Indo-European roots.]

from Wiktionary, Creative Commons Attribution/Share-Alike License

From Middle English certain, certein, from Old French certain, from Vulgar Latin unattested form *certānus, extended form of Latin certus ("fixed, resolved, certain"), of the same origin as cretus, past participle of cernere ("to separate, perceive, decide"). Displaced native Middle English wis, iwis ("certain, sure") (from Old English, ġewiss ("certain, sure") and alternative Middle English spelling sertane ("some, certain")


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  • However, you should note that many of the compilers (language processors) and commands on the PRIME will make certain assumptions if you follow certain guidelines.

    Phrack Issue #15 Elric of Imrryr's Issue 1987

  • [Footnote 1: «qua» is generally used instead of «quae» in the feminine nominative singular and in the neuter nominative and accusative plural.] «485. » «quīdam», _a certain one, a certain_

    Latin for Beginners Benjamin Leonard D'Ooge 1900

  • "I am terrified to say such a thing, but I am certain, quite _certain_, that the ship will be lost within the next few days."

    The Stowaway Girl Louis Tracy 1895

  • We can honor him, in certain ways -- in _certain_ ways, Raoul -- almost more than if he had never done wrong at all.

    The Inner Shrine Basil King 1893

  • Which certain people call a "_certain age_," [205]

    The Works of Lord Byron. Vol. 4 George Gordon Byron Byron 1806

  •  certain stresses and certain environmental conditions, would never have re - sulted in this behavior but did.

    TEDBUNDY Michaud, S G & Aynesworth H 1989

  • "Yes, I have at my command one method that is certain, -- _perfectly certain_.

    Fairy Fingers A Novel Anna Cora Ogden Mowatt Ritchie 1844

  • Asked what Kan meant by the term "certain progress," Noda said, "that's something that Kan said, so please ask him."

    Japan PM Strongly Attacked, Lukewarmly Defended, Over Resignation Plans William Sposato 2011

  • It's the certain in the phrase "certain tax preparers" that's still causing controversy. News Kelly Phillips Erb 2011

  • When we label certain kinds of books "boy books" we are not only reinforcing a certain idea of manliness that doesn't include all boys, we are also cutting boys and girls off from a lot of books they might actually like.

    Charles London: There Are No Boy Books Charles London 2011


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  • A contranym: both an indeterminate quality ("she has a certain air about her"), and an established fact (a certainty).

    May 15, 2008