sky vs throw back

sky is a noun but throw back is not a noun.

Word	Noun	Adjective	Verb	Adverb
sky	Yes	No	Yes	No
throw back	No	No	Yes	No

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

Other hyponyms of sky include submarine, lag, toss back.

sky (noun)	throw back (noun)
the atmosphere and outer space as viewed from the earth

sky (verb)	throw back (verb)
throw or toss with a light motion	throw back with a quick, light motion