refract vs ascertain

refract and ascertain both are verbs.

Word	Noun	Adjective	Verb	Adverb
refract	No	No	Yes	No
ascertain	No	No	Yes	No

As verbs, ascertain is a hypernym of refract; that is, ascertain is a word with a broader meaning than refract:

refract: determine the refracting power of (a lens)
ascertain: establish after a calculation, investigation, experiment, survey, or study

Other hypernyms of refract include determine, find, find out.

refract (verb)	ascertain (verb)
determine the refracting power of (a lens)	be careful or certain to do something; make certain of something
subject to refraction	learn or discover with certainty
	find out, learn, or determine with certainty, usually by making an inquiry or other effort
	establish after a calculation, investigation, experiment, survey, or study