murkiness vs opacity

murkiness and opacity both are nouns.

Word	Noun	Adjective	Verb	Adverb
murkiness	Yes	No	No	No
opacity	Yes	No	No	No

As nouns, opacity is a hypernym of murkiness; that is, opacity is a word with a broader meaning than murkiness:

murkiness: the quality of being cloudy
opacity: the quality of being opaque to a degree; the degree to which something reduces the passage of light

Other hypernyms of murkiness include opaqueness.

murkiness (noun)	opacity (noun)
the quality of being cloudy	the quality of being opaque to a degree; the degree to which something reduces the passage of light
an atmosphere in which visibility is reduced because of a cloud of some substance	incomprehensibility resulting from obscurity of meaning
	the phenomenon of not permitting the passage of electromagnetic radiation