sonar

Từ điển Oxford Advanced Learner 8th

sonar [sonar sonars] BrE [ˈsəʊnɑː(r)] NAmE [ˈsoʊnɑːr] noun uncountable
equipment or a system for finding objects underwater using sound waves
compare ↑radar

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

• Từ đồng nghĩa / Synonyms:
  echo sounder, asdic