1. noun A bitter, hard-fought conflict that ends in the death of one of the participants. The battle between this lion and water buffalo truly is a fight to the death—the victory of one ensures the demise of the other. The underground competition features experienced fighters from all over the world engaging in fights to the death.

2. noun An extremely difficult or serious challenge. Used hyperbolically. It was a fight to the death getting that old lawnmower working again, but by God I did it! We knew it would be a fight to the death negotiating the contract with their firm.

3. verb To engage in a bitter, hard-fought conflict that ends in the death of one of the participants. I know it's morbid, but one of the things I like best about nature documentaries is watching predators and their prey fighting to the death. The crime boss forced the two underlings to fight to the death, with the winner being spared any further punishment.