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

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.

Keep Reading on Vocabulary.com

Vocabulary lists containing ascertain

The Vocabulary.com Top 1000

Looking to grow your vocabulary? Check out this interactive, curated word list from our team of English language specialists at Vocabulary.com – one of over 17,000 lists we've built to help learners worldwide!

Night

Interested in learning more words like this one? Our team at Vocabulary.com has got you covered! You can review flashcards, quiz yourself, practice spelling, and more – and it's all completely free to use!

The Bill of Rights

Want to remember this word for good? Start your learning journey today with our library of interactive, themed word lists built by the experts at Vocabulary.com – we'll help you make the most of your study time!

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

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

From Los Angeles Times ● Aug. 2, 2026

Without further information, it is impossible to ascertain their validity.

From BBC ● Jul. 17, 2026

If the lawmakers wanted to ascertain U.S. policy, they could have asked the State Department.

From The Wall Street Journal ● Jul. 10, 2026

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

From Salon ● May 30, 2026

I told her I would ascertain the situation.

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

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

Mlle Helouin goes to Arches and ascertains that no one is near to listen.

From The Romance of a Poor Young Man A Drama Adapted from the French of Octave Feuillet by Pierrepont Edwards

The three women's recorded cause of death is yet to be ascertained, the court was also told.

From BBC ● May 29, 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

The cause of the collapse is still to be ascertained, and investigations are under way according to state government officials.

From BBC ● Jul. 10, 2025

Categories, functions, and meanings have to be ascertained empirically, by running little experiments such as substituting a phrase whose category you don’t know for one you do know and seeing whether the sentence still works.

From "The Sense of Style" by Steven Pinker

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

The 1967 Public Health Act already allows for officers to enter "any premises' at all" for the purpose of "ascertaining whether there is, or has been" any breach of the rules.

From BBC ● Oct. 10, 2024

"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

My companion followed me quickly, and cautiously drew the door to, after carefully ascertaining that the lock was a falling, and not a spring, one.

From "Dracula" by Bram Stoker

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