Echo-location (5)
(Other definitions for radar that I've seen before include "System for locating distant objects" , "Instrument to detect and locate distant objects" , "System for detecting things using radio waves" , "Aircraft detection system" , "Ranging system" .)
(Other definitions for sonar that I've seen before include "Underwater location equipment" , "Underwater detection device" , "Sub's navigation" , "Detection system at sea" , "System to locate underwater objects" .)