perspicuousness vs lucidity

perspicuousness and lucidity both are nouns.

Word	Noun	Adjective	Verb	Adverb
perspicuousness	Yes	No	No	No
lucidity	Yes	No	No	No

As nouns, lucidity is a hypernym of perspicuousness; that is, lucidity is a word with a broader meaning than perspicuousness:

perspicuousness: clarity as a consequence of being perspicuous
lucidity: free from obscurity and easy to understand; the comprehensibility of clear expression

Other hypernyms of perspicuousness include clarity, clearness, limpidity, lucidness, pellucidity.

perspicuousness (noun)	lucidity (noun)
clarity as a consequence of being perspicuous	free from obscurity and easy to understand; the comprehensibility of clear expression
	a lucid state of mind; not confused