1. vt. To cause to be broken (in any sense). "Your latest patch to the editor broke the paragraph commands."
2. v. (of a program) To stop temporarily, so that it may debugged. The place where it stops is a 'breakpoint'.
3. [techspeak] vi. To send an RS-232 break (125 msec of line high) over a serial comm line.
4. [UNIX] vi. To strike whatever key currently causes the tty driver to send SIGINT to the current process. Normally, break (sense 3) or delete does this.
5. 'break break' may be said to interrupt a conversation (this is an example of verb doubling).