mugging vs mug

mugging and mug both are nouns.

Word	Noun	Adjective	Verb	Adverb
mugging	Yes	No	No	No
mug	Yes	No	Yes	No

mugging (noun)	mug (noun)
assault with intent to rob	with handle and usually cylindrical
	the human face (`kisser' and `smiler' and `mug' are informal terms for `face' and `phiz' is British)
	a person who is gullible and easy to take advantage of
	the quantity that can be held in a mug

mugging (verb)	mug (verb)
	To stare awkwardly
	rob at gunpoint or with the threat of violence