Did you know?

Click any word in a definition or example to find the entry for that word

ascertain - definition and synonyms


What are red words?

90% of the time, speakers of English use just 7,500 words in speech and writing. These words appear in red, and are graded with stars. One-star words are frequent, two-star words are more frequent, and three-star words are the most frequent.



The thesaurus of synonyms and related words is fully integrated into the dictionary. Click on the thesaurus category heading under the button in an entry to see the synonyms and related words for that meaning.

verb [intransitive/transitive] formal ascertain pronunciation in British English /ˌæsə(r)ˈteɪn/
Word Forms
present tense
present participleascertaining
past tenseascertained
past participleascertained
  1. to find out something

    Police are trying to ascertain the facts of the case.

    ascertain whether/what/how etc:

    We need to ascertain whether the project is feasible.

    ascertain that:

    The police have ascertained that he knew the victim.

    ascertain from:

    This much could easily be ascertained from the newspapers.

    ascertain the cause/nature/extent of something:

    Experts were unable to ascertain the cause of the accident.


sea lion

in an online conversation, repeatedly asking a person questions which suggest that you are interested in what they are talking about, but are actually intended to annoy them

BuzzWord Article

Open Dictionary


an electric skateboard

add a word


A must for anyone with an interest in the changing face of language. The Macmillan Dictionary blog explores English as it is spoken around the world today.

global English and language change from our blog
Macmillan learn live love play