echo

Definitions

General English

Aviation

  • noun the return of a signal back to the source from which it was transmitted

Computing

  • verb to return a received signal along the same transmission path

Construction

  • The reflection of sound waves with a magnitude and time delay sufficient to be perceived by a listener as separate from sound communicated directly to the listener.

Electronics

  • A wave or signal which returns after being reflected. Such a wave or signal must have sufficient magnitude and delay so as to distinguish it from a direct wave or signal. An example is the repetition of a sound after being reflected off a hard surface.
  • The portion of a transmitted radar signal which a scanned object returns to the radar receiver. Also, the visual indication on a radar screen, such as a blip, of such a reflection. Also called radar echo, or return (3).
  • On the screen of a TV or radar receiver, an undesired condition in which duplicate images appear. May be due, for instance, to the simultaneous displaying of a direct signal and a reflected signal. Also called ghosting.
  • A repetition or reflection of a signal within a communications line. For instance, such an echo resulting from impedance mismatches along a telephone line.
  • A signal, other than the original signal, which is transmitted back to a sender. Used, for example, to test network connections. Also, the transmission of such a signal.

Medical

  • prefix
    (written as echo-)
    referring to sound

Military

  • noun a sound which is reflected by an object back towards the listener
  • noun
    (written as Echo)
    the fifth letter of the phonetic alphabet (Ee)

Origin & History of “echo”

Echo comes via Old French or Latin from Greek ēkhṓ, a word related to ēkhḗ ‘sound’. It may have originated as a personification of the concept ‘sound’, which developed eventually into the mythological mountain nymph Echo, who faded away for love of narcissus until nothing but her voice was left. (The Greek verb derived from ēkhḗ, ēkhein, is the ultimate source of English catechism.).
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