[ 'səʊnα: ]
■ noun
1》 a system for the detection of objects under water based on the emission and measured reflection of sound pulses.
↘an apparatus used for this.
2》 the method of echolocation used in air or water by animals such as whales and bats.
Origin
1940s: from so(und) na(vigation and) r(anging) , on the pattern of radar .