impinge on vs bump

impinge on is not a noun while bump is a noun.

Word	Noun	Adjective	Verb	Adverb
impinge on	No	No	Yes	No
bump	Yes	No	Yes	No

As verbs, bump is a hyponym of impinge on; that is, bump is a word with a more specific, narrower meaning than impinge on:

impinge on (noun)	bump (noun)
	an impact (as from a collision)
	something that bulges out or is protuberant or projects from its surroundings
	a lump on the body caused by a blow

impinge on (verb)	bump (verb)
hit against; come into sudden contact with	knock against with force or violence
	remove or force from a position of dwelling previously occupied
	to play music at loud volume
	to enjoy some music greatly
	dance erotically or dance with the pelvis thrust forward
	come upon, as if by accident; meet with
	assign to a lower position; reduce in rank