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
Derived Forms
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ascertainernoun
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ascertainmentnoun
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nonascertainablenessnoun
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nonascertainmentnoun
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preascertainmentnoun
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preascertainverb (used with object)
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ascertainableadjective
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nonascertainableadjective
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unascertainableadjective
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unascertainedadjective
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well-ascertainedadjective
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ascertainablyadverb
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nonascertainablyadverb
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unascertainablyadverb
Inflected Forms
Participles
Conjugated Forms
Present
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ascertainsimple
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ascertainssimple
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have ascertainedperfect
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has ascertainedperfect
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am ascertainingprogressive
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are ascertainingprogressive
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is ascertainingprogressive
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have been ascertainingperfect progressive
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has been ascertainingperfect progressive
Past
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ascertainedsimple
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had ascertainedperfect
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was ascertainingprogressive
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were ascertainingprogressive
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had been ascertainingperfect progressive
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.
Vocabulary lists containing ascertain
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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:
If the lawmakers wanted to ascertain U.S. policy, they could have asked the State Department.
From The Wall Street Journal ● Jul. 10, 2026
That’s what “I Shot Andy Warhol” wants the viewer to ascertain.
From Salon ● Apr. 29, 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
In a decision log, shown to the inquiry, Sanders recorded the need to liaise with the head of corporate communications, Matthew Jarram, to "ascertain what covenants can be imposed on the press".
From BBC ● Mar. 18, 2026
“Yes, we want to make sure Miss Amin wasn’t hurt because of this little snafu. We are simply trying to ascertain who might be spreading these lies about Mobius.”
From "Internment" by Samira Ahmed
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
In a word the method which teacheth to folow a right order, and exactly to enumerate all the circumstances of what we seek, contains, whatsoever ascertains the rules of Arithmatick.
From A Discourse of a Method for the Well Guiding of Reason and the Discovery of Truth in the Sciences by Descartes, René
The exact number of crew members could not be ascertained but the source added it could be between six and eight people.
From BBC ● Jan. 16, 2026
But from Thames Verlet drove straight to Marsden Wharf, where he visited the Rainbow Warrior, ate a piece of cake, and ascertained the schedule for the evening.
From Slate ● Jul. 22, 2025
Both Prieur and Mafart had been involved in planning the operation back in Paris—it was Prieur who had first ascertained the ship’s itinerary by calling Lloyd’s of London and posing as a journalist.
From Slate ● Jul. 22, 2025
Norfolk Police said the cause of death could not be ascertained from the post-mortem examination on Thursday.
From BBC ● Nov. 22, 2024
Thus far the facts ascertained corroborated Wells’ story most persuasively.
From "In Cold Blood" by Truman Capote
The return on the S&P 500 isn’t based on picking winners or ascertaining market sentiment.
From The Wall Street Journal ● May 21, 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
“Sourcing gold from the UAE is notoriously risky,” the report said, describing the difficulty in ascertaining the origins of the refined gold.
From Seattle Times ● May 30, 2024
"I am writing this letter to you, with the main purpose of ascertaining your feelings towards a subject well known to both of us," it began.
From BBC ● Feb. 26, 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
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
