certainty

American

[sur-tn-tee] / ˈsɜr tn ti /

noun

plural

certainties

the state of being certain.

Synonyms:

confidence, assurance, certitude
something certain; an assured fact.

Synonyms:

truth

idioms

for / of a certainty, certainly; without a doubt.

I suspect it, but I don't know it for a certainty.

certainty British

/ ˈsɜːtəntɪ /

noun

the condition of being certain
something established as certain or inevitable
without doubt

"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

Related Words

See belief.

Other Word Forms

noncertainty noun

Etymology

Origin of certainty

1250–1300; Middle English certeinte < Anglo-French, equivalent to certein certain + -te -ty ²

Explanation

A certainty is a sure thing, something we know is true or will happen without any doubt. Here's a certainty: One plus one is two. And here's another: The earth orbits the sun. The noun certainty comes from the Latin word certus, meaning "sure" or "fixed." Besides being something that is certain, the word can also refer to a state of mind, like the confidence you feel when you know something is completely true or right. For example, you might speak with certainty about your decision to move to the big city and pursue your dream of becoming a famous actor. (But that doesn't necessarily mean becoming a famous actor is a certainty.)

Keep Reading on Vocabulary.com

Vocabulary lists containing certainty

Spelling Practice 2, Unit 2

Looking to grow your vocabulary? Check out this interactive, curated word list from our team of English language specialists at Vocabulary.com – one of over 17,000 lists we've built to help learners worldwide!

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

There is less certainty around the effect on wildfire season in California.

From Los Angeles Times • Apr. 16, 2026

He added that the deal has brought "certainty" to the UK SMR programme after signing an early works agreement last year enabling the launch of site work in Czechia.

From BBC • Apr. 13, 2026

The lack of certainty over when the conflict will end has fueled some negative sentiment among investors, who had hoped for a deal between the two and a plan for reopening the waterway.

From MarketWatch • Apr. 13, 2026

If your "love" is a feeling of profound connection and unbreakable dedication, then my "love" is the mathematical certainty that my existence is meaningless without yours.

From The Wall Street Journal • Apr. 12, 2026

I felt my eyes water and knew with certainty that my teeth would be black for an hour.

From "The Detective's Assistant" by Kate Hannigan

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023