massacre

The killing of a considerable number (usually limited to people) where little or no resistance can be made, with indiscriminate violence, without necessity, and contrary to civilized norms.

Murder.

Any overwhelming defeat, as in a game or sport.

To kill in considerable numbers where little or no resistance can be made, with indiscriminate violence, without necessity, and contrary to civilized norms. (Often limited to the killing of human beings.)

To win so decisively it is in the manner of so slaughtering one's opponent.

To give a performance so poorly it is in the manner of so slaughtering the musical piece, play etc being performed.