Source : Webster's Revised Unabridged Dictionary (1913)

Harp \Harp\, v. i. [imp. & p. p. {Harped}p. pr. & vb. n.
   {Harping}.] [AS. hearpian. See {Harp}, n.]
   1. To play on the harp.

            I heard the voice of harpers, harping with their
            harps.                                --Rev. xiv. 2.

   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.

            Harping on what I am, Not what he knew I was.
                                                  --Shak.

   {To harp on one string}, to dwell upon one subject with
      disagreeable or wearisome persistence. [Collog.]