as·​cer·​tain ˌa-sər-ˈtān How to pronounce ascertain (audio)
ascertained; ascertaining; ascertains

transitive verb

: to find out or learn with certainty
ascertain the truth
trying to ascertain the cause of the fire
information that can be easily ascertained on the Internet
archaic : to make certain, exact, or precise
ascertainable adjective
ascertainment noun
Choose the Right Synonym for ascertain

discover, ascertain, determine, unearth, learn mean to find out what one did not previously know.

discover may apply to something requiring exploration or investigation or to a chance encounter.

discovered the source of the river

ascertain implies effort to find the facts or the truth proceeding from awareness of ignorance or uncertainty.

attempts to ascertain the population of the region

determine emphasizes the intent to establish the facts definitely or precisely.

unable to determine the origin of the word

unearth implies bringing to light something forgotten or hidden.

unearth old records

learn may imply acquiring knowledge with little effort or conscious intention (as by simply being told) or it may imply study and practice.

I learned her name only today
learning Greek

Examples of ascertain in a Sentence

We look at digital media—images, audio and video—and we try to ascertain whether or not they've been manipulated. We use mathematical and computational techniques to detect alterations in them. Claudia Dreifus, New York Times, 2 Oct. 2007
Currently, an official trying to ascertain road damage in the aftermath of an earthquake might have to keep one eye on the TV news while listening to both radio traffic reports and the police scanner. Since most of these data are available in digital form, the software could take them all in, process them and present a report outlining the best evacuation routes. Kevin Hogan, Technology Review, April 2002
With an equation linking the money wage to prices, the degree of inflation could be ascertained. Sidney Weintraub, Modern Economic Thought, (1977) 1993
Recent Examples on the Web Following Putin’s invasion of Ukraine, Beijing made sure to ascertain the United States’ red lines and largely tried to adhere to them. Alexander Gabuev, Foreign Affairs, 9 Apr. 2024 Concerned relatives were unable to ascertain their welfare or whereabouts while Daybell and Vallow lived alone in Hawaii, reportedly on the life insurance money Daybell received after his wife’s death. Miles Klee, Rolling Stone, 10 Apr. 2024 See all Example Sentences for ascertain 

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'ascertain.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


Middle English acertainen to inform, give assurance to, from Anglo-French acerteiner, from a- (from Latin ad-) + certein, certain certain

First Known Use

15th century, in the meaning defined at sense 2

Time Traveler
The first known use of ascertain was in the 15th century

Dictionary Entries Near ascertain

Cite this Entry

“Ascertain.” Dictionary, Merriam-Webster, Accessed 21 May. 2024.

Kids Definition


as·​cer·​tain ˌas-ər-ˈtān How to pronounce ascertain (audio)
: to learn with certainty : find out
could not ascertain the correct date
ascertainable adjective
ascertainment noun

More from Merriam-Webster on ascertain

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