impinging vs touching

impinging and touching both are nouns.

Word	Noun	Adjective	Verb	Adverb
impinging	Yes	No	No	No
touching	Yes	Yes	No	No

As nouns, touching is a hyponym of impinging; that is, touching is a word with a more specific, narrower meaning than impinging:

Other hyponyms of impinging include collision, hit, engagement, interlocking, mesh, meshing, flick, impact, touch.

impinging (noun)	touching (noun)
the physical coming together of two or more things	the act of putting two things together with no space between them
	the event of something coming in contact with the body

impinging (adjective)	touching (adjective)
	arousing affect