| Noun | 1. | asdic - a measuring instrument that sends out an acoustic pulse in water and measures distances in terms of the time for the echo of the pulse to return; sonar is an acronym for sound navigation ranging; asdic is an acronym for anti-submarine detection investigation committeepinger - a pulse generator used for echo sounding in sonar pulse generator - a generator of single or multiple voltage pulses; usually adjustable for pulse rate | |