verb as·cer·tain \ˌa-sər-ˈtān\

Definition of ascertain

  1. transitive verb
  2. 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

  3. 2 archaic :  to make certain, exact, or precise


play \-ˈtā-nə-bəl\ adjective


play \-ˈtān-mənt\ noun

Examples of ascertain in a sentence

  1. 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

  2. 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

  3. With an equation linking the money wage to prices, the degree of inflation could be ascertained. —Sidney Weintraub, Modern Economic Thought, (1977) 1993

Origin and Etymology of ascertain

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

Synonym Discussion of 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.

ASCERTAIN Defined for Kids


verb as·cer·tain \ˌa-sər-ˈtān\

Definition of ascertain for Students




  1. :  to find out with certainty Police tried to ascertain the cause of the accident.

Seen and Heard

What made you want to look up ascertain? Please tell us where you read or heard it (including the quote, if possible).


a rounded knoll or a ridge of ice

Get Word of the Day daily email!


Take a 3-minute break and test your skills!

Name That Thing

Test your visual vocabulary with our 10-question challenge!


Test Your Knowledge - and learn some interesting things along the way.