Synonyms

ascertain

American

[as-er-tayn] / 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

Inflected Forms

Participles

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.

See Examples For:

ascertain ascertains ascertained ascertaining

Earlier, in a statement posted on its website, the park said its emergency response procedures had been "immediately activated" and it was "working closely with the authorities to ascertain exactly what happened".

From BBC ● Oct. 10, 2026

US non-farm payrolls figures later Friday are in focus as traders try to ascertain the Fed's next move after last month's rate hike.

From Barron's ● Oct. 2, 2026

“We are working to ascertain his identity and the motivations.”

From Los Angeles Times ● Aug. 2, 2026

“He was nearby on the scene there, and we were working trying to ascertain his identity and the motivations behind that,” Hicks said.

From The Wall Street Journal ● Aug. 2, 2026

But I am not at all certain it will be possible to ascertain their whereabouts at this stage.'

From "The Remains of the Day" by Kazuo Ishiguro

Henry plays it safe: He ascertains John is gay so shares his chapters via mail.

From Washington Post ● Dec. 29, 2022

On the other hand, logical analysis ascertains whether the premises of an argument support the conclusion.

From Textbooks ● Jun. 15, 2022

“Insikt Group ascertains with high confidence that the top tools on underground forums will continue to change,” the report said.

From Fox News ● Jul. 27, 2019

“The court looks at the impact and the motivation - if it is an ethical violation, if it is an administrative violation - and then ascertains if the punishment fits the crime,” Grevemberg said.

From Washington Times ● Apr. 2, 2018

The chairman regulates the proceedings of the Board, and ascertains its resolutions.

From Blackwood's Edinburgh Magazine, Vol. 60, No. 373, November 1846 by Various

More information should have been ascertained from care home staff, he said.

From BBC ● Oct. 6, 2026

A third person whose injuries had yet to be ascertained was in the process of being brought to hospital.

From Barron's ● Aug. 21, 2026

The cause of the fire is yet to be ascertained.

From BBC ● Jun. 23, 2026

She’s ascertained that she’s not a child and not an adult; not the sick little girl named Marcy who she used to be, nor her maker’s favorite.

From Salon ● Sep. 24, 2025

I ascertained that they wished me to perform, and it behove me to comply, that I might avoid detection.

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

Deciding the punishment should be quicker than ascertaining guilt, but nothing is certain in this case.

From BBC ● Sep. 27, 2026

The export control amounts to a de facto ban on the model since Anthropic has no way of ascertaining the nationality of its users.

From The Wall Street Journal ● Jun. 16, 2026

And if you’re brave enough to step deeper into the lot, yet clearly not confident in ascertaining a Golden Pothos from a Pothos N’Joy, a woman with a warm smile will approach you kindly.

From Los Angeles Times ● Mar. 13, 2025

"Studying isolated enzymes is a powerful tool for ascertaining their activity and drawing conclusions about their functional role inside the plant cell," Hart explained.

From Science Daily ● Apr. 24, 2024

“Miss Miggery, my dear, I do not want to appear too forward so early in our acquaintance, but may I inquire, am I right in ascertaining that you have aspirations?”

From "The Tale of Despereaux: Being the Story of a Mouse, a Princess, Some Soup and a Spool of Thread" by Kate DiCamillo

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