Also a similar thing in explosives: the thing normally found inside a electric detonator, that initiates the detonator. AKA a match.
Not to be confused with a damp squib, which is loosely packed gunpowder in a non-water-proof container, used for heaving, which unfortunately has gotten wet (as such things occasionally do when placed underground).
Squibs are used to discharge fire extinguishing agents on aircraft, as part of engine, APU, landing gear or other fire protection systems. I knew the term and knew they were electrically activated by a sensor, but never looked into them to understand that they were basically explosives too. Cool!
A squibb is member of a boats crew, a squid is swimming underneath the boat.