explore vs plumb

explore is not a noun while plumb is a noun.

Word	Noun	Adjective	Verb	Adverb
explore	No	No	Yes	No
plumb	Yes	Yes	Yes	Yes

As verbs, plumb is a hyponym of explore; that is, plumb is a word with a more specific, narrower meaning than explore:

explore (noun)	plumb (noun)
	the metal bob of a plumb line

explore (adjective)	plumb (adjective)
	exactly vertical

explore (verb)	plumb (verb)
inquire into	adjust with a plumb line so as to make vertical
travel to or penetrate into	measure the depth of something
inquire into a subject in detail	examine thoroughly and in great depth
examine (organs) for diagnostic purposes	weight with lead

explore (adverb)	plumb (adverb)
	conforming to the direction of a plumb line
	exactly
	completely; used as intensifiers