The definition of sonar is a system that sends out sound waves and measures how long it takes for them to be reflected and returned as a way to detect the depth of water or to find objects under water.(noun)
An example of sonar is a system wherein you send out sound waves and see how long it takes to bounce them back in order to try to find out how deep an area is in the Atlantic Ocean.
See sonar in Webster's New World College Dictionary
Origin: so(und) n(avigation) a(nd) r(anging)
See sonar in American Heritage Dictionary 4
Origin: so(und) na(vigation and) r(anging).
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