[1] : The Collaborative International Dictionary of English v.0.48

echo \ech"o\ e^k"-o, n.; pl. echoes e^k"=oz. l.
   echo, gr. 'hchw` echo, sound, akin to 'hchh`, 'h^chos, sound,
   noise; cf. skr. v=a,c to sound, bellow; perh. akin to e.
   voice: cf. f. 'echo.
   1. a sound reflected from an opposing surface and repeated to
      the ear of a listener; repercussion of sound; repetition
      of a sound.
      1913 webster

            the babbling echo mocks the hounds.   --shak.
      1913 webster

            the woods shall answer, and the echo ring. --pope.
      1913 webster

   2. fig.: sympathetic recognition; response; answer.
      1913 webster

            fame is the echo of actions, resounding them.
                                                  --fuller.
      1913 webster

            many kind, and sincere speeches found an echo in his
            heart.                                --r. l.
                                                  stevenson.
      1913 webster

   3.
      a myth.  poetic a wood or mountain nymph, regarded as
          repeating, and causing the reverberation of them.
          1913 webster

                sweet echo, sweetest nymph, that liv'st unseen
                within thy airy shell.            --milton.
      b gr. myth. a nymph, the daughter of air and earth,
          who, for love of narcissus, pined away until nothing
          was left of her but her voice.
          1913 webster

                compelled me to awake the courteous echo
                to give me answer from her mossy couch.
                                                  --milton.
          1913 webster

   4. whist, contract bridge
      a a signal, played in the same manner as a trump signal,
          made by a player who holds four or more trumps or as
          played by some exactly three trumps and whose partner
          has led trumps or signaled for trumps.
      b a signal showing the number held of a plain suit when
          a high card in that suit is led by one's partner.
          webster 1913 suppl.

   echo organ mus., a set organ pipes inclosed in a box so
      as to produce a soft, distant effect; -- generally
      superseded by the swell.

   echo stop mus., a stop upon a harpsichord contrived for
      producing the soft effect of distant sound.

   to applaud to the echo, to give loud and continuous
      applause. --m. arnold.
      1913 webster

            i would applaud thee to the very echo,
            that should applaud again.            --shak.
      1913 webster
see also:
echoes echo organ echo stop to applaud to the echo 

Applaud >> A Words
Applaud, definition of term: Applaud
applaud_pag1.html

Echo >> E Words
Echo, definition of term: Echo
echo_pag1.html

Echo Sounding >> E Words
Echo Sounding, definition of term: Echo Sounding
echo+sounding_pag1.html