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.

synoniemen: asdic, echo sounder.

Roget 466: measurement, admeasurement^†, mensuration, survey, valuation, appraisement, assessment, assize; estimate, estimation; dead reckoning, reckoning etc. (numeration) 85; gauging etc. v.; horse power.    metrology, weights and measures, compound arithmetic.    measure, yard measure, standard, rule, foot rule, compass, calipers; gage, gauge; meter, line, rod, check; dividers; velo^†.    flood mark, high water mark; Plimsoll line; index etc. 550.    scale; graduation, graduated scale; nonius^†; vernier etc. (minuteness) 193.    [instruments for measuring] bathometer, galvanometer, heliometer, interferometer, odometer, ombrometer^†, pantometer^†, pluviometer^†, pneumatometer^†, pneumometer^†, radiometer, refractometer, respirometer, rheometer, spirometer^†, telemeter, udometer^†, vacuometer^†, variometer^†, viameter^†, thermometer, thermistor (heat) etc. 382, barometer (air) etc. 338, anemometer (wind) 349, dynamometer, goniometer, (angle) 244 meter; landmark etc. (limit) 233; balance, scale etc. (weight) 319; marigraph^†, pneumatograph^†, stethograph^†; rain gauge, rain gage; voltmeter (volts), ammeter (amps); spectrophotometer (light absorbance); mass spectrophotometer (molecular mass); geiger counter, scintillation counter (radioactivity); pycnometer (liquid density); graduated cylinder, volumetric flask (volume); radar gun (velocity); radar (distance); side-looking radar, (shape, topography); sonar (depth in water); light meter (light intensity); clock, watch, stopwatch, chronometer (time); anemometer (wind velocity); densitometer (color intensity). measurability, computability, determinability^†.    coordinates, ordinate and abscissa, polar coordinates, latitude and longitude, declination and right ascension, altitude and azimuth.    geometry, stereometry^†, hypsometry^†; metage^†; surveying, land surveying; geodesy, geodetics^†, geodesia^†; orthometry^†, altimetry^†; cadastre [Fr.].    astrolabe, armillary sphere^†.    land surveyor; geometer.    ... meer laten zien

Roget 208: depth; deepness etc. adj.; profundity, depression etc. (concavity) 252.    hollow, pit, shaft, well, crater; gulf etc. 198; bowels of the earth, botttomless pit^†, hell.    soundings, depth of water, water, draught, submersion; plummet, sound, probe; sounding rod, sounding line; lead.    bathymetry.    [instrument to measure depth] sonar, side-looking sonar; bathometer^†.    ... meer laten zien

Nederlands: sonar, sonarapparatuur
Pools: sonar