happiness vs felicity

happiness and felicity both are nouns.

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

As nouns, happiness and felicity are synonyms defined as:

happiness and felicity: state of well-being characterized by emotions ranging from contentment to intense joy

happiness (noun)	felicity (noun)
emotions experienced when in a state of well-being	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	state of well-being characterized by emotions ranging from contentment to intense joy