Synonyms & Antonyms of certain

1 known but not named
  • a certain person told me that today is your birthday

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2 having or showing a mind free from doubt
  • I'm certain that they'll arrive on time

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4 impossible to avoid or evade
  • as he got older, the athlete began to feel the certain effects of the aging process on his body

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5 not likely to fail
  • chicken soup is grandma's certain cure for pretty much whatever ails you

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See the Dictionary Definition 

Frequently Asked Questions About certain

How does the adjective certain contrast with its synonyms?

Some common synonyms of certain are cocksure, positive, and sure. While all these words mean "having no doubt or uncertainty," 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

When would cocksure be a good substitute for certain?

In some situations, the words cocksure and certain are roughly equivalent. However, cocksure implies presumptuous or careless positiveness.

you're always so cocksure about everything

When is it sensible to use positive instead of certain?

While the synonyms positive and certain are close in meaning, positive intensifies sureness or certainty and may imply opinionated conviction or forceful expression of it.

I'm positive that's the person I saw

When could sure be used to replace certain?

The words sure and certain are synonyms, but do differ in nuance. Specifically, sure usually stresses the subjective or intuitive feeling of assurance.

felt sure that I had forgotten something

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Time Traveler for certain

Time Traveler

The first known use of certain was in the 13th century

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Cite this Entry

“Certain.” Thesaurus, Merriam-Webster, Accessed 24 Jan. 2022.

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More from Merriam-Webster on certain

Nglish: Translation of certain for Spanish Speakers

Britannica English: Translation of certain for Arabic Speakers


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