FUSE or FUZE, an appliance for firing explosives in blasting operations, military shells, etc. (see BLASTING and AMMUNITION). The spelling is not governed by authority, but modern convenience has dictated the adoption of the "z" by military engineers as a general rule, in order to distinguish this sense from that of melting by heat (see below) . The word, according to the New English Dictionary, is one of the forms in which the Lat. fusus, spindle, has been adapted through Romanic into English, the ordinary fuze taking the shape of a spindle-like tube.
In electrical engineering a "fuse" (always so spelled) is a safety device, commonly consisting of a strip or wire of easily fusible metal, which melts and thus interrupts the circuit of which it forms part, whenever that circuit, through some accident or derangement, is caused to carry a current larger than that for which it is intended. In this sense the word must be connected with fusus, the past participle of Lat. fundere, to pour, whence comes the verb "fuse," to melt by heat.