sonar

noun

1. (uncountable, usually)Artificial echolocation by use of electronic equipment, with hydrophones to locate objects underwater, using the same wave-analysis principles that radar uses.

   “They were able to detect the sunken wreck using sonar.”

2. (countable)A device that provides such echolocation.

   “They finally bought a new sonar to replace the 40-year-old unit that sometimes didn't work right.”

3. (broadly, countable, uncountable)Any echolocation.

   “Submarines and bats both use sonar to navigate.”

4. (alt-of, countable, dated, uncountable)Dated form of sonar.