keep back vs wink

keep back is not a noun while wink is a noun.

Word	Noun	Adjective	Verb	Adverb
keep back	No	No	Yes	No
wink	Yes	No	Yes	No

As verbs, wink is a hyponym of keep back; that is, wink is a word with a more specific, narrower meaning than keep back:

keep back (noun)	wink (noun)
	a reflex that closes and opens the eyes rapidly
	closing one eye quickly as a signal
	a very short time (as the time it takes the eye to blink or the heart to beat)

keep back (verb)	wink (verb)
prevent the action or expression of	briefly shut the eyes
hold back; refuse to hand over or share	keep back by blinking
secure and keep for possible future use or application	signal by winking
	gleam or glow intermittently