ascertain

verb

as·​cer·​tain ˌa-sər-ˈtān 

ascertained; ascertaining; ascertains

transitive verb

1

: 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

2

archaic : to make certain, exact, or precise

ascertainable

ˌa-sər-ˈtā-nə-bəl 

adjective

ascertainment

ˌa-sər-ˈtān-mənt 

noun

Synonyms

• discover
• realize
• see
• hear
• learn
• find

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

This letter stressed the necessity of large scale experimentation to ascertain the possibility of producing an atom bomb. —Andrew Paul, Popular Science, 25 June 2025

The attack came as global markets were trying to ascertain what lays ahead after the U.S. struck key Iranian nuclear facilities over the weekend with a barrage of 30,000-pound bunker busting bombs and Tomahawk missiles. —Emma Burleigh, Fortune, 23 June 2025

The attack came as global markets were trying to ascertain what lays ahead after the U.S. struck key Iranian nuclear facilities over the weekend with a barrage of 30,000-pound bunker-busting bombs and Tomahawk missiles. —Aamer Madhani, Twin Cities, 23 June 2025

Global markets were also trying to ascertain what lays ahead after the U.S. struck key Iranian nuclear facilities over the weekend with a barrage of 30,000-pound bunker busting bombs and Tomahawk missiles. —Aamer Madhani, Chicago Tribune, 23 June 2025

Word History

Etymology

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

Rhymes for ascertain

• aeroplane
• appertain
• capitaine
• cassegrain
• cellophane
• chatelaine
• counterpane
• entertain
• gethsemane
• halothane
• hurricane
• hyperplane

Kids Definition

ascertain

verb

as·​cer·​tain ˌas-ər-ˈtān 

: to learn with certainty : find out

could not ascertain the correct date

ascertainable

-ˈtā-nə-bəl 

adjective

ascertainment

-ˈtān-mənt 

noun