/ek'oh loh kay"sheuhn/ , n.
1. the general method of locating objects by determining the time for an echo to return and the direction from which it returns, as by radar or sonar.
2. Zool. the sonarlike system used by dolphins, bats, and other animals to detect and locate objects by emitting usually high-pitched sounds that reflect off the object and return to the animal's ears or other sensory receptors.
[ 1944; ECHO + LOCATION ]