ENGLISH
REFERENCE

certain

adj. · det. · pron.
US //ˈsɝtən// UK //sˈɜːtən// cer·tain
  1. 1 sure or confident (adj.)
    A2 Elementary

    to be completely sure about something in your mind.

    convinced of the truth of a particular fact or idea; possessing no doubt.

    Example

    I am certain that I locked the front door before we left.

    Example

    The researchers are certain of their findings, having replicated the experiment under controlled conditions three times.
    Pitfall
    I am certain for the results.
    I am certain of the results.

    Use the preposition 'of' or 'about' after certain when followed by a noun phrase.

  2. 2 inevitable (adj.)
    B1 Intermediate

    sure to happen; something that cannot be avoided.

    inevitable or destined to occur; established as a factual certainty.

    Example

    It is certain that the sun will rise tomorrow morning.

    Example

    Failure was almost certain once the primary engine lost pressure during the ascent.
Show 3 more sensesShow fewer
  1. 3 specific but unnamed (det.)
    B1 Intermediate

    used to talk about a particular person or thing without giving their name or exact details.

    referring to a specific but unspecified individual, group, or thing; often used to introduce a topic without exhaustive detail.

    Example

    A certain person told me that you were looking for a new job.

    Example

    There are certain risks involved in this investment that we must discuss before signing the contract.
  2. 4 limited or some (adj.)
    B2 Upper Intermediate

    used to describe a limited amount of a quality, like 'a certain amount of luck'.

    denoting a limited or definite extent or degree of a quality.

    Example

    You need a certain amount of patience to teach young children.

    Example

    The project requires a certain level of expertise that the current staff does not yet possess.
  3. 5 some members of a group (pron.)
    C1 Advanced Formal

    some people or things in a group, but not all of them.

    referring to an unspecified but restricted number of members within a larger set.

    Example

    Certain of the guests decided to leave the party early.

    Example

    Certain of the documents were found to be forged, casting doubt on the entire legal proceeding.
Origin

From Middle English certeyn, certein, certain, borrowed from Old French certain, from a 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”).

Word family

© 2026 English Reference