sonar vs. radar

sonar

noun

  1. a method for detecting and locating objects submerged in water by echolocation.
  2. the apparatus used in sonar.

radar

noun

  1. Electronics. a device for determining the presence and location of an object by measuring the time for the echo of a radio wave to return from it and the direction from which it returns.
  2. a means or sense of awareness or perception:

    lobbyists working under the media's radar.