jocosity (n.)

"given to jokes and jesting," 1670s, from Latin iocosus "full of jesting, fond of jokes, funny," from iocus "pastime, sport; a jest, joke" (see joke (n.)). Often it implies ponderous humor (compare jocund). Related: Jocosely; jocoseness.

word-forming element making abstract nouns from adjectives and meaning "condition or quality of being ______," from Middle English -ite, from Old French -ete (Modern French -ité) and directly from Latin -itatem (nominative -itas), suffix denoting state or condition, composed of -i- (from the stem or else a connective) + the common abstract suffix -tas (see -ty (2)).

Roughly, the word in -ity usually means the quality of being what the adjective describes, or concretely an instance of the quality, or collectively all the instances; & the word in -ism means the disposition, or collectively all those who feel it. [Fowler]