JEC (Japanese Electrotechnical Committee) - A regional standards group.
JIC (Joint International Congress) - an international standards group that focuses on electrical standards. They drafted the relay logic standards.
JIT (Just in Time) - a philosophy when setting up and operating a manufacturing system such that materials required arrive at the worksite just in time to be used. This cuts work in process, storage space, and a number of other logistical problems, but requires very dependable supplies and methods.
jog - a mode where a motor will be advanced while a button is held, but not latched on. It is often used for clearing jams, and loading new material.
jump - a forced branch in a program
jumper - a short wire, or connector to make a permanent setting of hardware parameters.