v.1. To drive someone or something away, especially by fighting or hitting: Two robbers attacked me on the subway, but I beat them off with my bag. After a long battle, the soldiers beat off the invaders.
2. To defeat someone or something in a competition: Our company intends to beat off our rivals for the contract. The visiting team was behind us for most of the game, but beat us off squarely in the end.
3. Vulgar Slang To masturbate. Used of males.