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

to ring or echo with sound, to repeat

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

The signal reflected by a radar target

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

- Liu Yue