swimming vs skinny-dip

swimming and skinny-dip both are nouns.

Word	Noun	Adjective	Verb	Adverb
swimming	Yes	Yes	No	No
skinny-dip	Yes	No	Yes	No

As nouns, skinny-dip is a hyponym of swimming; that is, skinny-dip is a word with a more specific, narrower meaning than swimming:

Other hyponyms of swimming include bathe, dip, plunge, dive, diving, floating, natation, skin-dive, skin diving.

swimming (noun)	skinny-dip (noun)
the act of swimming	a naked swim

swimming (adjective)	skinny-dip (adjective)
applied to a fish depicted horizontally
filled or brimming with tears

swimming (verb)	skinny-dip (verb)
	bathe in the nude