n. the repetition of a sound resulting from reflection of the sound waves, to reply in a sympathetic or identical tone as to sentiments expressed; a close parallel of words, styles and thoughts, etc; repeater
 
vi. to ring or echo with sound, to repeat
 
vt. to repeat in imitation, agreement, or flattery; to send (voices, etc.)
 
(of a computer) to display (a character) on the screen of a visual display unit as a response to receiving that character from a keyboard entry
 
(radio) the signal reflected by a radar target
a reflected television or radio or radar beam

Echo
n. (Greek mythology) a nymph who was spurned by Narcissus and pined away until only her voice remained.