ascertain

[as-er-teyn]

verb (used with object)

1. to find out definitely; learn with certainty or assurance; determine.

   to ascertain the facts.

2. Archaic.,  to make certain, clear, or definitely known.

ascertain

/ ˌæsəˈteɪn /

verb

1. to determine or discover definitely

2. archaic,  to make certain

Other Word Forms

• ascertainable adjective
• ascertainably adverb
• ascertainer noun
• ascertainment noun
• nonascertainable adjective
• nonascertainableness noun
• nonascertainably adverb
• nonascertainment noun
• preascertain verb (used with object)
• preascertainment noun
• unascertainable adjective
• unascertainably adverb
• unascertained adjective
• well-ascertained adjective

Word History and Origins

Origin of ascertain¹

First recorded in 1400–50; late Middle English, variant of acertain, assertain, from Middle French acertain-, stem of acertener “to make certain”; equivalent to a- ⁵ + certain

Word History and Origins

Origin of ascertain¹

C15: from Old French acertener to make certain

Example Sentences

Speaking at a news conference on Monday, officials said the incident was a "targeted act of violence", but said they had not yet ascertained Sanford's motive.

From BBC

The team ascertain that she isn't street homeless, take her details, offer her a voucher and move on.

From BBC

She’s ascertained that she’s not a child and not an adult; not the sick little girl named Marcy who she used to be, nor her maker’s favorite.

From Salon

And if the Board of Supervisors doesn’t allow further seismic study of the building, the county won’t be able to ascertain the potential risks of doing no retrofit work, some warn.

From Los Angeles Times

"This investigation has been ongoing since an initial report was made to Wiltshire Police in 2023 and detailed inquiries have been undertaken since to ascertain the facts," he added.

From BBC

Related Words

• confirm 
• determine 
• divine 
• double-check 
• find out 
• verify 

When To Use

What are other ways to say ascertain?

To ascertain something is to determine it or learn it with certainty or assurance. How is ascertain different from the learn, discover, and detect? Find out on Thesaurus.com.