thud /ˈθʌd/
  砰擊聲,重擊(vi.)砰的一聲掉下,轟的一聲
  Thud n.  A dull sound without resonance, like that produced by striking with, or striking against, some comparatively soft substance; also, the stroke or blow producing such sound; as, the thrud of a cannon ball striking the earth.
     At every new thud of the blast, a sob arose.   --Jeffrey.
     At intervals there came some tremendous thud on the side of the steamer.   --C. Mackay.
  Thud v. i. & t. To make, or strike so as to make, a dull sound, or thud.
     Hardly the softest thudding of velvety pads.    --A. C. Doyle.
     The waves break into spray, dash and rumble and thud below your feet.    --H. F. Brown.
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  thud
       n : a heavy dull sound (as made by impact of heavy objects)
           [syn: thump, thumping, clump, clunk]
       v 1: make a dull sound; "the knocker thudded against the front
            door" [syn: thump]
       2: strike with a dull sound; "Bullets were thudding against the
          wall"
       3: make a noise typical of an engine lacking lubricants [syn: crump,
           scrunch]
       [also: thudding, thudded]