covert vs flock

covert and flock both are nouns.

Word	Noun	Adjective	Verb	Adverb
covert	Yes	Yes	No	No
flock	Yes	No	Yes	No

As nouns, flock is a hypernym of covert; that is, flock is a word with a broader meaning than covert:

covert (noun)	flock (noun)
a covering that serves to conceal or shelter something	a group of birds
a flock of coots	a group of sheep or goats
	a church congregation guided by a pastor
	an orderly crowd
	(often followed by `of') a large number or amount or extent

covert (adjective)	flock (adjective)
secret or hidden; not openly practiced or engaged in or shown or avowed
(of a wife) being under the protection of her husband

covert (verb)	flock (verb)
	come together as in a cluster or flock
	move as a crowd or in a group