English has words that cannot be trusted without context.
A contronym is a word with two meanings that contradict each other. It may also be called an auto-antonym, an autantonym, or—more appropriately—a Janus word.
Janus was the Roman god of doors, thresholds, beginnings, and endings. He is usually shown with two faces: one looking forward, the other looking back.
His words do the same.
To cleave is to cling together or split apart.
To bolt is to secure something in place or flee from it.
To screen is to show something or conceal it.
To sanction is to authorize an act or penalize it.
Oversight can mean careful supervision or a failure to notice.
To dust is to remove fine particles or apply them.
To trim is to decorate something or cut part of it away.
Fast can mean moving rapidly or fixed firmly in place.
To weather something is to withstand it. To be weathered by it is to be worn away.
The word has not changed.
Only its direction has.
Context decides which face we see.
NB: A word can face both directions and remain correctly read.