brutality (n.)

mid-15c., "bestial, pertaining to or resembling an animal" (as opposed to a man), from Old French brutal, from Latin brutus (see brute (adj.)). Of persons, "unintelligent, unreasoning" (1510s); "fierce, savage, cruel, inhuman, unfeeling" (1640s). Related: Brutally.

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]