Fuse

1. A safety device that protects an electric circuit from excessive current, consisting of or containing a metal element that melts when current exceeds a specific amperage, thereby opening the circuit. Also sometimes spelled a fuze. Always keep some spare fuses on hand.
2. A cord of readily combustible material that is lighted at one end to carry a flame along its length to detonate an explosive a the other end. We lit the fuse and ran as fast as we could.
3. To be mixed or united by or as if by melting together. The thermite fused the mechanism of the gun to as to make it unusable.