felicity vs felicitousness

felicity and felicitousness both are nouns.

Word	Noun	Adjective	Verb	Adverb
felicity	Yes	No	No	No
felicitousness	Yes	No	No	No

As nouns, felicity and felicitousness are synonyms defined as:

felicity and felicitousness: pleasing and appropriate manner or style (especially manner or style of expression)

felicity (noun)	felicitousness (noun)
pleasing and appropriate manner or style (especially manner or style of expression)	pleasing and appropriate manner or style (especially manner or style of expression)
state of well-being characterized by emotions ranging from contentment to intense joy