The Collaborative International Dictionary of English v.0.48:

Harp \Harp\, v. t.
   To play on, as a harp; to play (a tune) on the harp; to
   develop or give expression to by skill and art; to sound
   forth as from a harp; to hit upon.
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         Thou 'st harped my fear aright.          --Shak.
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The Collaborative International Dictionary of English v.0.48:

Harp \Harp\ (h[aum]rp), n. [OE. harpe, AS. hearpe; akin to D.
   harp, G. harfe, OHG. harpha, Dan. harpe, Icel. & Sw. harpa.]
   1. A musical instrument consisting of a triangular frame
      furnished with strings and sometimes with pedals, held
      upright, and played with the fingers.
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   2. (Astron.) A constellation; Lyra, or the Lyre.
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   3. A grain sieve. [Scot.]
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   Aeolian harp. See under Aeolian.
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   Harp seal (Zool.), an arctic seal (Phoca Gr[oe]nlandica).
      The adult males have a light-colored body, with a
      harp-shaped mark of black on each side, and the face and
      throat black. Called also saddler, and saddleback. The
      immature ones are called bluesides; their fur is white,
      and they are killed and skinned to harvest the fur.

   Harp shell (Zool.), a beautiful marine gastropod shell of
      the genus Harpa, of several species, found in tropical
      seas. See Harpa.
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The Collaborative International Dictionary of English v.0.48:

Harp \Harp\, v. i. [imp. & p. p. Harped (h[aum]rpt) p. pr. &
   vb. n. Harping.] [AS. hearpian. See Harp, n.]
   1. To play on the harp.
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            I heard the voice of harpers, harping with their
            harps.                                --Rev. xiv. 2.
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   2. To dwell on or recur to a subject tediously or
      monotonously in speaking or in writing; to refer to
      something repeatedly or continually; -- usually with on or
      upon. "Harpings upon old themes." --W. Irving.
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            Harping on what I am,
            Not what he knew I was.               --Shak.
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   To harp on one string, to dwell upon one subject with
      disagreeable or wearisome persistence. [Colloq.]
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WordNet (r) 3.0 (2006):

harp
    n 1: a chordophone that has a triangular frame consisting of a
         sounding board and a pillar and a curved neck; the strings
         stretched between the neck and the soundbox are plucked
         with the fingers
    2: a pair of curved vertical supports for a lampshade
    3: a small rectangular free-reed instrument having a row of free
       reeds set back in air holes and played by blowing into the
       desired hole [syn: harmonica, mouth organ, harp, mouth
       harp]
    v 1: come back to; "Don't dwell on the past"; "She is always
         harping on the same old things" [syn: harp, dwell]
    2: play the harp; "She harped the Saint-Saens beautifully"