Answered from No Such Thing As The Otters Circling · No Such Thing As A Fish · 2026-11-05
The panel traced it to a 1920 US Congress hearing on transporting explosives, where officials wanted to tell dangerous military fuzes apart from ordinary commercial fuses. The Z spelling marked the military device, the part that detonates a warhead, while the S spelling stayed for everyday fuses like those on fireworks.
Source: our own transcription of the episode. The full conversation is on No Such Thing As A Fish (2026-11-05). Read the whole episode summary →