impinge on vs spat

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

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

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

impinge on (noun)	spat (noun)
	a young oyster or other bivalve
	a cloth covering (a legging) that covers the instep and ankles
	a quarrel about petty points

impinge on (verb)	spat (verb)
hit against; come into sudden contact with	clap one's hands together
	spawn
	engage in a brief and petty quarrel
	clap one's hands or shout after performances to indicate approval
	strike with a sound like that of falling rain
	become permanently attached
	come down like raindrops