(1) A repetition of a signal in a communications line. The difference in electrical characteristics at opposite ends can cause the echo.
(2) In communications, to transmit received data back to the sending station allowing the user to inspect what was received. A "local echo" displays what is typed on screen.
(3) (Echo) A family of popular virtual assistants from Amazon with the Alexa technology. See
Amazon Echo.
(4) A DOS/Windows command that displays messages and turns off/on screen responses. See
batch file abc's.