What does ascertain mean?
Ascertain is a verb meaning to discover or establish something with certainty, usually through deliberate investigation, inquiry, or examination. When you ascertain a fact, you do not merely guess or suppose — you take steps to confirm it, whether by asking questions, checking records, conducting tests, or weighing evidence. The word carries a distinctly formal register and is especially common in journalism, law, science, and official reports: investigators ascertain the cause of an accident, auditors ascertain where funds went, and lawyers ascertain the terms of an agreement. Typical constructions include "attempt to ascertain," "impossible to ascertain," and "ascertain whether or how something occurred." Derived from the same root as "certain," the word literally suggests making something certain — moving it from doubt into confirmed knowledge. For writers who want to convey rigor and precision rather than casual curiosity, ascertain is an invaluable choice.
verbTo find out or determine something with certainty, typically by making careful inquiry, investigation, or examination.
- To find out or make certain of a fact by investigation, inquiry, or examination.
- (Law) To establish conclusively, as in determining liability or the value of property.
"Investigators worked through the night to ascertain the cause of the crash."
"The auditors were unable to ascertain how the discrepancy had arisen."
"She rang the embassy to ascertain what documents she would need for the visa."
"Ascertain" was once so formal that 18th-century writers used it for anything from settling a legal dispute to confirming the price of turnips — today it's the word of choice whenever certainty matters.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of ascertain
Ascertain entered English in the early 15th century, borrowed from Anglo-Norman French acertainir, ultimately built on the Latin certus, meaning "fixed" or "sure" — the same root that gives English "certain" and "certainty." Its earliest sense involved making something legally certain or settled, particularly resolving disputes, before it evolved into its modern sense of discovering facts through inquiry. Cognates sharing the Latin root include certify, certify's relative certificate, and concern.
Related word forms
How ascertain is actually used
Ascertain is relatively formal and is most at home in professional, journalistic, academic, and legal writing. In everyday conversation people more often say "find out." It frequently appears in constructions such as "it is difficult to ascertain" and in indirect questions ("ascertain whether...", "ascertain how...").
Easily confused with ascertain
Ascertain means to find something out with certainty, while attain means to succeed in reaching or achieving a goal.
Ascertain means to determine a fact, while sustain means to support, maintain, or endure over time.