perspicuousness vs pellucidity

perspicuousness and pellucidity both are nouns.

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

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

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

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

perspicuousness (noun)	pellucidity (noun)
clarity as a consequence of being perspicuous	passing light without diffusion or distortion
	free from obscurity and easy to understand; the comprehensibility of clear expression