Some words are their own opposite

'Cleave' can mean to split apart or to stick firmly together — a collision of two separate Old English words, cleofan and clifian, that happened to converge into the same modern spelling. 'Sanction' can mean to officially permit something or to punish it. These self-contradicting words are called contronyms, or auto-antonyms, and they arise either from two word histories colliding, as with cleave, or from a single word's meaning drifting in two directions at once.

— Wikipedia contributors, Contronym — Also called auto-antonyms or Janus words