A device, capable of changing from one to the next of a sequence of distinguishable states upon receipt of an input signal.
Note: One specific type is a circuit that produces one output pulse each time it receives some predetermined number of input pulses.
Reference: I.E.E.E. (extract)
Please note that this is the term as it stands in the original IALA Dictionary edition (1970-1989)
International Association of Marine Aids to Navigation and Lighthouse Authorities - AISM