sonar - abbreviation for 'sound navigation and ranging'
asdic - abbreviation for 'allied submarine detection investigation committee'. Underwater acoustic detecting system which transmits a pulse and receives a reflection from underwater objects, particularly submarines, at a distance. Also used by trawlers to detect shoals of fish. Equivalent to US 'sonar', now preferred term.
1963. In order to conform with NATO practice, the name Asdic..has been superseded by the word Sonar, the Admiralty announced yesterday... In future Asdic ratings will be known as Sonar operators.
