sonar

Definitions of sonar
1

n 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”
Synonyms:
asdic, echo sounder
Type of:
measuring device, measuring instrument, measuring system
instrument that shows the extent or amount or quantity or degree of something
navigational instrument
an instrument used for navigating

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