Brutal

google

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late 15th century (in the sense ‘relating to the lower animals’): from Old French, or from medieval Latin brutalis, from brutus ‘dull, stupid’ (see brute).

wiktionary

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From Medieval Latin brutalis(“savage, stupid”), from Latin brūtus(“dull, stupid”).

etymonline

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brutal (adj.)

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.