ascertain
- 01 C1 Advanced
to find out the true facts about a situation or a piece of information.
to discover or determine something with certainty; to establish a fact through investigation.
Simple“The police are trying to ascertain the cause of the fire.”
In context“The committee conducted a thorough investigation to ascertain whether the safety protocols had been followed correctly during the emergency.”
UsageThis verb is transitive and requires a direct object, often a 'that' clause or a 'whether' clause.
Teacher's tipThis is a high-register word; in everyday conversation, native speakers usually prefer 'find out' or 'check'.
- 02 C2 Proficiency
to make sure that something happens or is true.
to ensure or make certain of an outcome or a fact.
Simple“The contract was written to ascertain that both parties received equal payment.”
In context“The ancient laws were designed to ascertain the rights of the landowners against any claims from the crown.”
UsageIn modern English, this sense is almost entirely replaced by 'ensure' or 'guarantee'.
Teacher's tipLearners should be aware of this sense in older literature but avoid using it in modern business or academic writing.
“Our most striking discovery was ascertaining that painted pottery production continued by constantly evolving.”
“It only recently became possible to ascertain a more precise date thanks to new tree ring records from similar elevations in the Pacific Northwest.”
From Middle English acerteynen, from Old French acertener, from a- (“to, towards”) + certener (“make sure of”), from the adjective certain, from Latin certus (“certain, fixed”). Compare to Spanish acertar.
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.