extravagancy vs inordinateness

extravagancy and inordinateness both are nouns.

Word	Noun	Adjective	Verb	Adverb
extravagancy	Yes	No	No	No
inordinateness	Yes	No	No	No

As nouns, inordinateness is a hypernym of extravagancy; that is, inordinateness is a word with a broader meaning than extravagancy:

extravagancy: the quality of exceeding the appropriate limits of decorum or probability or truth
inordinateness: immoderation as a consequence of going beyond sufficient or permitted limits

Other hypernyms of extravagancy include excess, excessiveness.

extravagancy (noun)	inordinateness (noun)
the quality of exceeding the appropriate limits of decorum or probability or truth	immoderation as a consequence of going beyond sufficient or permitted limits