enemigo
/eneˈmiɡo/ · A2 · adj
enemy
en- (not) + amigo (friend): an enemigo is literally a not-friend
From Latin inimicus = in- (not) + amicus (friend), the same root that gives English enemy and inimical. Swap the first letters of amigo for enem- and a friend becomes a foe. As an adjective it means hostile or adverse.