SELSYN

selsyn, synchro

(noun) a system consisting of a generator and a motor so connected that the motor will assume the same relative position as the generator; the generator and the motor are synchronized

Source: WordNet® 3.1

Etymology

Short for self-synchronizing.

Noun

selsyn (plural selsyns)

A synchro whose currents are used directly to drive a receiver synchro that rotates in unison with the synchro transmitter.

Source: Wiktionary