Meaning

noun an opposing military force

noun an armed adversary (especially a member of an opposing military force)

noun any hostile group of people

originFrom Middle English enemy, enemye, enmy, borrowed from Old French enemi, anemi (Modern French ennemi), from Latin inimīcus, from in- (“not”) + amīcus (“friend”). Displaced Middle English fend (“enemy”), from Old English fēond (“enemy”), which survived into Modern English as fiend, but with a different meaning. Doublet of inimic.

Etymology from Wiktionary, CC BY-SA 3.0