noun

sonar

SOH-nar/ˈsəʊnɑːr/

A system or device that uses sound waves to detect underwater objects.

The ship uses sonar to detect rocks and fish underwater.

Ship sonar cutaway: transducer below hull sends curved sound pulses toward underwater rock and fish, reflected returning pulses in different color, clear echo detection, no labels.

Etymology

soEnglishsound waves

+naEnglishfinding or directing a course

+rEnglishdistance measurement

Sound, navigation, and ranging describe the system’s purpose: using sound to locate things and measure their distance. Underwater, reflected sound supplies the information needed to detect objects.

In context

Rick Steves' Europe2:01

… we went underwater, partly in my own little, photographic hide, Machan. Having failed to encounter a beast, we resorted to sonar in the 1980s -- sort of underwater radar.

Loch Ness: Scotland's Legendary Lake - Rick Steves’ Europe Travel Guide - Travel Bite

More examples

The search team uses sonar to locate the sunken boat.
A portable sonar helps anglers find fish beneath the ice.
The submarine's sonar detects another vessel nearby.

Forms

sonar · sonars

Similar words

echolocation: Echolocation also includes animals locating objects through reflected sound.
echo sounding: Echo sounding specifically measures water depth using reflected sound.