move ahead vs limp

move ahead is not a noun while limp is a noun.

Word	Noun	Adjective	Verb	Adverb
move ahead	No	No	Yes	No
limp	Yes	Yes	Yes	No

As verbs, limp is a hyponym of move ahead; that is, limp is a word with a more specific, narrower meaning than move ahead:

Other hyponyms of move ahead include head, trace, roar, wander.

move ahead (noun)	limp (noun)
	the uneven manner of walking that results from an injured leg

move ahead (adjective)	limp (adjective)
	lacking or having lost rigidity
	without energy or will

move ahead (verb)	limp (verb)
move ahead; travel onward in time or space	walk impeded by some physical limitation or injury
	proceed slowly or with difficulty