A repeater for use in a four-wire or four-wire type circuit in which there are two amplifiers, one amplifying the signals in one channel and the other amplifying the signals in the other channel of the circuit.
Reference: I.E.C. (modified)
Please note that this is the term as it stands in the original IALA Dictionary edition (1970-1989)
Celsius (previously Centigrade)
International Association of Marine Aids to Navigation and Lighthouse Authorities - AISM