plethora vs excess

plethora and excess both are nouns.

Word	Noun	Adjective	Verb	Adverb
plethora	Yes	No	No	No
excess	Yes	Yes	No	No

As nouns, excess is a hypernym of plethora; that is, excess is a word with a broader meaning than plethora:

plethora: extreme excess
excess: immoderation as a consequence of going beyond sufficient or permitted limits

Other hypernyms of plethora include excessiveness, inordinateness.

plethora (noun)	excess (noun)
extreme excess	excessive indulgence
	immoderation as a consequence of going beyond sufficient or permitted limits
	a quantity much larger than is needed
	the state of being more than full

plethora (adjective)	excess (adjective)
	more than is needed, desired, or required