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

Derived Forms

• ˌascerˈtainable, adjective
• ˌascerˈtainment, noun
• ˌascerˈtainably, adverb

Other Words From

• ascer·taina·ble adjective
• ascer·taina·bly adverb
• ascer·tainer noun
• ascer·tainment noun
• nonas·cer·taina·ble adjective
• nonas·cer·taina·ble·ness noun
• nonas·cer·taina·bly adverb
• nonas·cer·tainment noun
• preas·cer·tain verb (used with object)
• preas·cer·tainment noun
• unas·cer·taina·ble adjective
• unas·cer·taina·bly adverb
• unas·cer·tained adjective
• well-ascer·tained 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

The 1967 Public Health Act already allows for officers to enter "any premises' at all" for the purpose of "ascertaining whether there is, or has been" any breach of the rules.

From BBC

In terms of the quantity of the gas being expelled, scientists ascertained that ionised- and neutral-gas outflows measured by their equipment ultimately reached "0.14–2.9 and 30–100 solar mass per year, respectively."

From Salon

But how easily its meaning is ascertained raises questions about whether "DEI hire" is a dog whistle in the traditional sense, more slur-adjacent as some suggest, or something new.

From Salon

In her post-debate reaction, MSNBC’s Rachel Maddow repeated the wisdom many TV experts have shared about debates, which is that you can ascertain all you need to know with the sound off.

From Salon

It is impossible to ascertain the exact number of babies they may have killed, given the way the data was gathered.

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.