cease
To stop or come to an end completely.
Cease means to stop or come to an end completely and definitively. When a noise ceases, it stops completely. When a factory ceases operations, it shuts down and no longer produces anything. When someone asks you to cease talking during a movie, they want you to stop right away.
Cease suggests a complete stopping, a full ending rather than a temporary pause. A teacher might ask students to cease their chattering when it's time to focus on a lesson. A referee might order players to cease fighting and return to the game. During a truce, armies agree to cease hostilities and stop attacking each other.
You'll often see cease paired with other words in formal phrases. A ceasefire is an agreement to stop fighting. When something happens without cease, it continues nonstop, never ending. The phrase cease and desist appears in legal warnings telling someone to stop doing something immediately and not start again.
Cease sounds more formal than simply saying “stop” or “quit.” You'd probably tell your brother to stop bothering you, but a news report might say that heavy rains ceased after three days of flooding.