To break off means to separate a piece from something larger, usually suddenly or with some force. When you break off a chunk of chocolate from a candy bar, you snap it away from the rest. A branch might break off a tree during a storm, or you might break off the corner of a cracker to share with a friend.

The phrase also means to suddenly stop or end something, especially a relationship or conversation. If two countries break off diplomatic relations, they stop communicating officially. When friends break off their friendship, they decide to stop being friends. You might break off a conversation mid-sentence if you suddenly remember something urgent, or break off studying to grab a snack.

In both meanings, there's a sense of separation and suddenness. Whether it's a physical piece snapping away or an activity coming to an abrupt end, breaking off suggests a clean, decisive split rather than a gradual fade.