Definition of sonar in US English:



  • 1A system for the detection of objects under water and for measuring the water's depth by emitting sound pulses and detecting or measuring their return after being reflected.

    as modifier ‘a weak sonar signal’
    • ‘Out in the Atlantic, vast Japanese factory ships work nonstop, using modern sonar detection to spot the tuna shoals they sweep the ocean clean of fish.’
    • ‘Now, video footage and sonar data proves conclusively that the wreck is not Centaur.’
    • ‘The SUNS system can determine positions underwater by the use of small buoys which broadcast the position and time references by sonar signals.’
    • ‘And evidence that sonar kills whales goes way beyond coincidence.’
    • ‘For instance, he said, its active and passive sonar systems are aging, thus shortening the range of its monitoring.’
    1. 1.1 An apparatus used in a sonar system.
      ‘we reduced the sensitivity of our scanning sonars’
      • ‘Autosub will be using sonars to study the seabed.’
      • ‘They will be equipped with the latest survey systems, including multi-beam echo sounders and modern side-scan sonars, as well as the most advanced navigation and communications systems.’
      • ‘It just seemed to me that it would be more interesting to have things like submarine sonars and old grandfather clocks and lines from famous movies and bird songs and things like that.’
      • ‘Acms receives data from the sonars and other sensors and, through advanced algorithms and data handling, displays real time images on the command consoles.’
      • ‘It is equipped with a ham radio set, personal computer, global positioning system, two sonars, autopilot and wind wane which steers the boat depending on the direction of the wind.’
    2. 1.2 The method of echolocation used in air or water by animals such as bats or whales.
      ‘the fishing nets are detectable by dolphin sonar’
      • ‘Hearing the unusual ping, the animals might turn on their echolocators - their sonar - and then they can sense the net.’
      • ‘The animal's sensitive sonar is capable of picking up information about the shape of distant objects, and it was trained to respond in some distinctive way to this piece of information.’
      • ‘While the animals lack sonar, they do posses superb directional underwater hearing and the ability to see in near-darkness.’
      • ‘The knowledge the researchers gain about bat sonar is tested out on dolphins and applied to human sonar systems.’
      • ‘They believe that by being in the water with the animals and feeling their sonar they too are receiving a ‘healing’.’


1940s: from so(und) na(vigation and) r(anging), on the pattern of radar.