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Synonyms

ascertain

American

[as-er-teyn] / ˌæs ərˈteɪn /

verb (used with object)

to find out definitely; learn with certainty or assurance; determine.

to ascertain the facts.
Archaic. to make certain, clear, or definitely known.

ascertain British

/ ˌæsəˈteɪn /

verb

to determine or discover definitely
archaic to make certain

"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

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

Derived Forms

Conjugated Forms

Present

Past

Future

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

Explanation

Ascertain is a verb that means to find out something. You might have to go to the bank to ascertain if there is any money in your account. This is a formal word that often applies to discovering the facts or truth about something through examination or experimentation. Information that is ascertained is certain beyond a doubt. If you want a less formal synonym, use discover.

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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.

We just never noticed because we kept looking down at our feet, trying to ascertain a way out.

From Salon • May 30, 2026

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

But there is a suggestion the Italy midfielder is open to leaving St James' Park this summer, with his representatives understood to be scoping out the market to ascertain which clubs may be interested.

From BBC • Mar. 19, 2026

AFP and SourceMaterial used trade data, including some supplied by T&E, shareholder agreements, and customs documents obtained through freedom of information requests to ascertain the identities of three of those arrested.

From Barron's • Mar. 16, 2026

He had, since the whipping, seemed in a perpetual irritation, glowering around the rooms, leaving company often, saying he wished to ascertain whether matter still subsisted in his chamber.

From "The Astonishing Life of Octavian Nothing, Traitor to the Nation, Volume I: The Pox Party" by M.T. Anderson

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