flack vs criticism

flack and criticism both are nouns.

Word	Noun	Adjective	Verb	Adverb
flack	Yes	No	No	No
criticism	Yes	No	No	No

As nouns, criticism is a hypernym of flack; that is, criticism is a word with a broader meaning than flack:

Other hypernyms of flack include unfavorable judgment.

flack (noun)	criticism (noun)
artillery designed to shoot upward at airplanes	a serious examination and judgment of something
intense adverse criticism	disapproval expressed by pointing out faults or shortcomings
a slick spokesperson who can turn any criticism to the advantage of their employer	a written evaluation of a work of literature