blink vs hold back

blink is a noun but hold back is not a noun.

Word	Noun	Adjective	Verb	Adverb
blink	Yes	No	Yes	No
hold back	No	No	Yes	No

As verbs, hold back is a hypernym of blink; that is, hold back is a word with a broader meaning than blink:

Other hypernyms of blink include keep, keep back, restrain.

blink (noun)	hold back (noun)
a reflex that closes and opens the eyes rapidly

blink (verb)	hold back (verb)
briefly shut the eyes	prevent the action or expression of
keep back by blinking	hold back, as of a danger or an enemy; check the expansion or influence of
gleam or glow intermittently	hold back; keep from being perceived by others
	secure and keep for possible future use or application
	wait before acting
	refrain from doing