English Reference
noun

certainty

n.
US /ˈsɝtənti/ UK /sˈɜːtənti/ cer·tain·ty UK spelling certainties

  1. 01 B2 Upper Intermediate

    the feeling of being completely sure that something is true or will happen.

    the psychological state of being confident or certain about a proposition or outcome.

    Simple

    I can say with certainty that we will finish the project on time.

    In context

    Despite the conflicting evidence, the witness spoke with such absolute certainty that the jury found her testimony highly persuasive.

    Usage

    Often used in the phrase 'with certainty' or 'a sense of certainty'.

  2. 02 B2 Upper Intermediate

    something that is definitely true or that will definitely happen.

    an established fact or an event that is inevitable.

    Simple

    It is a certainty that prices will rise again next year.

    In context

    In the volatile world of venture capital, there is no such thing as a mathematical certainty, regardless of how promising a startup appears.

    Usage

    Commonly used with the definite article as 'a certainty'.

I had decided, with the particular certainty children sometimes develop about the rules of the world they are entering, that I would eat as little as possible before sixth grade.

Aeon· 21 Aug 2026

But the climate crisis is not only a future certainty, it is past and present truth.

The Guardian· 16 Aug 2026

From Middle English certeynte (“surety”), from Anglo-Norman certeinte, from Old French certeinete, from Vulgar Latin *certānitās, from Latin certus.

Etymology adapted from Wiktionary, available under CC BY-SA 4.0.

This entry
Origin Latin certus
Level B2 · Upper Intermediate
Frequency Frequent
Updated