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adjective cer·tain \ˈsər-tən\

Simple Definition of certain

  • : not having any doubt about something : convinced or sure

  • —used with it to say that something is known to be true or correct

  • —used to refer to something or someone that is not named specifically

Source: Merriam-Webster's Learner's Dictionary

Full Definition of certain

  1. 1 :  fixed, settled <a certain percentage of the profit>

  2. 2 :  of a specific but unspecified character, quantity, or degree <the house has a certain charm>

  3. 3 a :  dependable, reliable <a certain remedy for the disease> b :  known or proved to be true :  indisputable <it is certain that we exist>

  4. 4 a :  inevitable <the certain advance of age> b :  incapable of failing :  destined —used with a following infinitive <she is certain to do well>

  5. 5 :  assured in mind or action <I am certain they are right>

for certain

  1. :  as a certainty :  assuredly <the cause is not known for certain>

of a certain age

  1. :  of a somewhat advanced age :  no longer young <remembered by people of a certain age>

Examples of certain in a sentence

  1. I'm fairly certain that I'll be on time.

  2. <a certain person told me that today is your birthday>

Origin and Etymology of certain

Middle English, from Anglo-French, from Vulgar Latin *certanus, from Latin certus, from past participle of cernere to sift, discern, decide; akin to Greek krinein to separate, decide, judge, Old Irish criathar sieve

First Known Use: 13th century

Synonym Discussion of certain

sure, certain, positive, cocksure mean having no doubt or uncertainty. sure usually stresses the subjective or intuitive feeling of assurance <felt sure that I had forgotten something>. certain may apply to a basing of a conclusion or conviction on definite grounds or indubitable evidence <police are certain about the cause of the fire>. positive intensifies sureness or certainty and may imply opinionated conviction or forceful expression of it <I'm positive that's the person I saw>. cocksure implies presumptuous or careless positiveness <you're always so cocksure about everything>.



pronoun, plural in construction cer·tain

Definition of certain

  1. :  certain ones

15th Century

First Known Use of certain

15th century

CERTAIN Defined for Kids



adjective cer·tain \ˈsər-tən\

Definition of certain for Students

  1. 1 :  without any doubt :  sure <Are you certain you saw her?>

  2. 2 :  known to be true <It's certain that they were here.>

  3. 3 :  known but not named <A certain person told me.>

  4. 4 :  being fixed or settled <a certain percentage of the profit>

  5. 5 :  bound by the way things are <Our plan is certain to succeed.>

  6. 6 :  sure to have an effect <a certain cure>



pronoun cer·tain

Definition of certain for Students

  1. :  known ones that are not named <Certain of the students could work harder.>

Seen and Heard

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a very small amount

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