Entries linking to amiability
The form and sense were confused in Old French with amable "lovable" (from Latin amare "to love"), and by 16c. the English word also had a secondary sense of "exciting love or delight," especially by having an agreeable temper and a kind heart. The word was subsequently reborrowed by English in Latin form without the sense contamination as amicable.
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]