The Collaborative International Dictionary of English v.0.48:

Thump \Thump\, n. [Probably of imitative origin; perhaps
   influenced by dump, v. t.]
   1. The sound made by the sudden fall or blow of a heavy body,
      as of a hammer, or the like.
      [1913 Webster]

            The distant forge's swinging thump profound.
                                                  --Wordsworth.
      [1913 Webster]

            With heavy thump, a lifeless lump,
            They dropped down, one by one.        --Coleridge.
      [1913 Webster]

   2. A blow or knock, as with something blunt or heavy; a heavy
      fall.
      [1913 Webster]

            The watchman gave so great a thump at my door, that
            I awaked at the knock.                --Tatler.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Thump \Thump\, v. t. [imp. & p. p. Thumped; p. pr. & vb. n.
   Thumping.]
   To strike or beat with something thick or heavy, or so as to
   cause a dull sound.
   [1913 Webster]

         These bastard Bretons; whom our hathers
         Have in their own land beaten, bobbed, and thumped.
                                                  --Shak.
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The Collaborative International Dictionary of English v.0.48:

Thump \Thump\, v. i.
   To give a thump or thumps; to strike or fall with a heavy
   blow; to pound.
   [1913 Webster]

         A watchman at midnight thumps with his pole. --Swift.
   [1913 Webster]

WordNet (r) 3.0 (2006):

thump
    n 1: a heavy dull sound (as made by impact of heavy objects)
         [syn: thump, thumping, clump, clunk, thud]
    2: a heavy blow with the hand
    v 1: move rhythmically; "Her heart was beating fast" [syn:
         beat, pound, thump]
    2: make a dull sound; "the knocker thudded against the front
       door" [syn: thud, thump]
    3: hit hard with the hand, fist, or some heavy instrument; "the
       salesman pounded the door knocker"; "a bible-thumping
       Southern Baptist" [syn: thump, pound, poke]