Echolocation

a means of locating an object using an emitted sound and the reflection back from it

Echocardiogram

a noninvasive technique that uses ultrasound to record the functioning of the heart

Echoic

formed in imitation of some natural sound

Echolalia

involuntary parrot-like repition of a word or phrase just spoken by another;echoing

anechoic

free from echoes and reverberations

lithosphere

the outer part of the solid earth composed of rock

Paleolithic

related to the early stone age

Eoanthropus

a genus of early man (comprising only the Piltdown man); dawn man

Eolith

a very early and crude stone tool

Lithography

the process or method of printing from a metal or stone surface

Eocene

relating to the second epoch of the Tertiary period