"quality of being cat-like," 1848; see feline + -ity.
Entries linking to felinity
feline adj.
"cat-like," 1680s, from Late Latin felinus "of or belonging to a cat," from Latin feles (genitive felis) "cat, wild cat, marten," which is of uncertain origin. Hence Modern Latin Felis, the cat genus. As a noun, "a feline animal" (popularly "a domestic cat") from 1861.
-ity
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]