late 15c., from Middle French hostile "of or belonging to an enemy" (15c.) or directly from Latin hostilis "of an enemy, belonging to or characteristic of the enemy; inimical," from hostis, in earlier use "a stranger, foreigner," in classical use "an enemy," from PIE root *ghos-ti- "stranger, guest, host." The noun meaning "hostile person" is recorded from 1838, American English, a word from the Indian wars. Related: Hostilely.