ascertain
Americanverb (used with object)
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to find out definitely; learn with certainty or assurance; determine.
to ascertain the facts.
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Archaic. to make certain, clear, or definitely known.
verb
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to determine or discover definitely
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archaic to make certain
Usage
What are other ways to say ascertain?
To ascertain something is to determine it or learn it with certainty or assurance. How is ascertain different from the learn, discover, and detect? Find out on Thesaurus.com.
Other Word Forms
- ascertainable adjective
- ascertainably adverb
- ascertainer noun
- ascertainment noun
- nonascertainable adjective
- nonascertainableness noun
- nonascertainably adverb
- nonascertainment noun
- preascertain verb (used with object)
- preascertainment noun
- unascertainable adjective
- unascertainably adverb
- unascertained adjective
- well-ascertained adjective
Etymology
Origin of ascertain
First recorded in 1400–50; late Middle English, variant of acertain, assertain, from Middle French acertain-, stem of acertener “to make certain”; equivalent to a- 5 + certain
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.
Officials said they are also in communication with authorities to ascertain the cause of death, obtain the complete medical record and review the circumstances surrounding the death.
From Los Angeles Times • Mar. 30, 2026
Her parents then took no measures to ascertain if the infection had been passed on and did not arrange for any medical visits or any vaccinations for their child.
From BBC • Mar. 12, 2026
In her separate opinion, Jackson began with the congressional reports in order to ascertain “Congress’ objective” before going to the statute’s text, reversing the order of Kagan’s analysis.
From Slate • Mar. 4, 2026
“With an asset this volatile, it’s impossible to ascertain when and where the bottom lies,” says Clark Bellin, president and chief investment officer at Bellwether Wealth.
From Barron's • Feb. 6, 2026
Gwenforte raised her head to ascertain the reason that he had stopped stroking her back.
From "The Inquisitor's Tale" by Adam Gidwitz
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
