stub vs impinge on

stub is a noun but impinge on is not a noun.

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

As verbs, impinge on is a hypernym of stub; that is, impinge on is a word with a broader meaning than stub:

Other hypernyms of stub include collide with, hit, run into, strike.

stub (noun)	impinge on (noun)
the small unused part of something (especially the end of a cigarette that is left after smoking)
a torn part of a ticket returned to the holder as a receipt
the part of a check that is retained as a record
a short piece remaining on a trunk or stem where a branch is lost
a small piece

stub (verb)	impinge on (verb)
strike (one's toe) accidentally against an object	hit against; come into sudden contact with
clear of weeds by uprooting them
extinguish by crushing
pull up (weeds) by their roots