The Collaborative International Dictionary of English v.0.48:

Echo \Ech"o\, v. t. [imp. & p. p. Echoed; p. pr. & vb. n.
   Echoing. -- 3d pers. sing. pres. Echoes.]
   1. To send back (a sound); to repeat in sound; to
      reverberate.
      [1913 Webster]

            Those peals are echoed by the Trojan throng.
                                                  --Dryden.
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            The wondrous sound
            Is echoed on forever.                 --Keble.
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   2. To repeat with assent; to respond; to adopt.
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            They would have echoed the praises of the men whom
            they envied, and then have sent to the newspaper
            anonymous libels upon them.           --Macaulay.
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The Collaborative International Dictionary of English v.0.48:

Echo \Ech"o\ ([e^]k"[-o]), n.; pl. Echoes ([e^]k"[=o]z). [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. ['e]cho.]
   1. A sound reflected from an opposing surface and repeated to
      the ear of a listener; repercussion of sound; repetition
      of a sound.
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            The babbling echo mocks the hounds.   --Shak.
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            The woods shall answer, and the echo ring. --Pope.
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   2. Fig.: Sympathetic recognition; response; answer.
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            Fame is the echo of actions, resounding them.
                                                  --Fuller.
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            Many kind, and sincere speeches found an echo in his
            heart.                                --R. L.
                                                  Stevenson.
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   3.
      (a) (Myth. & Poetic) A wood or mountain nymph, regarded as
          repeating, and causing the reverberation of them.
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                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.
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                Compelled me to awake the courteous Echo
                To give me answer from her mossy couch.
                                                  --Milton.
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   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.
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            I would applaud thee to the very echo,
            That should applaud again.            --Shak.
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The Collaborative International Dictionary of English v.0.48:

Echo \Ech"o\, v. i.
   To give an echo; to resound; to be sounded back; as, the hall
   echoed with acclamations. "Echoing noise." --Blackmore.
   [1913 Webster]

WordNet (r) 3.0 (2006):

echo
    n 1: the repetition of a sound resulting from reflection of the
         sound waves; "she could hear echoes of her own footsteps"
         [syn: echo, reverberation, sound reflection,
         replication]
    2: (Greek mythology) a nymph who was spurned by Narcissus and
       pined away until only her voice remained
    3: a reply that repeats what has just been said
    4: a reflected television or radio or radar beam
    5: a close parallel of a feeling, idea, style, etc.; "his
       contention contains more than an echo of Rousseau"; "Napoleon
       III was an echo of the mighty Emperor but an infinitely
       better man"
    6: an imitation or repetition; "the flower arrangement was
       created as an echo of a client's still life"
    v 1: to say again or imitate; "followers echoing the cries of
         their leaders" [syn: repeat, echo]
    2: ring or echo with sound; "the hall resounded with laughter"
       [syn: resound, echo, ring, reverberate]
    3: call to mind; "His words echoed John F. Kennedy" [syn:
       echo, recall]

The Free On-line Dictionary of Computing (19 January 2023):

echo

   1. A topic group on FidoNet's echomail system.

   Compare newsgroup.

   2. A Unix command that just prints its arguments.

   [Jargon File]