so·nar 
/ˈsoʊˌnɑɚ/ noun
/ˈsoʊˌnɑɚ/ noun [noncount] : a device used for finding things that are underwater by using sound waves
▪ They detected the submarine by using sonar. ▪ a sonar signal
▪ They detected the submarine by using sonar. ▪ a sonar signal
