swim vs plunge

swim and plunge both are nouns.

Word	Noun	Adjective	Verb	Adverb
swim	Yes	No	Yes	No
plunge	Yes	No	Yes	No

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

Other hyponyms of swim include bathe, skinny-dip, dip, dive, diving, floating, natation, skin-dive, skin diving.

swim (noun)	plunge (noun)
the act of swimming	a brief swim in water
	a steep and rapid fall

swim (verb)	plunge (verb)
travel through water	begin with vigor
be afloat either on or below a liquid surface and not sink to the bottom	devote (oneself) fully to
move as if gliding through water	cause to be immersed
be covered with or submerged in a liquid	immerse briefly into a liquid so as to wet, coat, or saturate
be dizzy or giddy	thrust or throw into
	fall abruptly
	drop steeply
	dash violently or with great speed or impetuosity