unambiguity vs clearness

unambiguity and clearness both are nouns.

Word	Noun	Adjective	Verb	Adverb
unambiguity	Yes	No	No	No
clearness	Yes	No	No	No

As nouns, clearness is a hypernym of unambiguity; that is, clearness is a word with a broader meaning than unambiguity:

unambiguity: clarity achieved by the avoidance of ambiguity
clearness: free from obscurity and easy to understand; the comprehensibility of clear expression

Other hypernyms of unambiguity include clarity, limpidity, lucidity, lucidness, pellucidity.

unambiguity (noun)	clearness (noun)
clarity achieved by the avoidance of ambiguity	free from obscurity and easy to understand; the comprehensibility of clear expression
	the quality of clear water