"make coarse, gross, or inhuman, lower to the level of a brute," 1740, from brutal + -ize. Related: Brutalized; brutalizing. An earlier verb was brutify (1660s), from French brutifier. Related: Brutification.
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 used to make verbs, Middle English -isen, from Old French -iser/-izer, from Late Latin -izare, from Greek -izein, a verb-forming element denoting the doing of the noun or adjective to which it is attached.
The variation of -ize and -ise began in Old French and Middle English, perhaps aided by a few words (such as surprise, see below) where the ending is French or Latin, not Greek. With the classical revival, English partially reverted to the correct Greek -z- spelling from late 16c. But the 1694 edition of the authoritative French Academy dictionary standardized the spellings as -s-, which influenced English.
In Britain, despite the opposition to it (at least formerly) of OED, Encyclopaedia Britannica, the Times of London, and Fowler, -ise remains dominant. Fowler thinks this is to avoid the difficulty of remembering the short list of common words not from Greek which must be spelled with an -s- (such as advertise, devise, surprise). American English has always favored -ize. The spelling variation involves about 200 English verbs.