The Collaborative International Dictionary of English v.0.48:

Tamp \Tamp\, v. t. [imp. & p. p. Tamped; p. pr. & vb. n.
   Tamping.] [Cf. F. tamponner to plug or stop. See
   Tampion.]
   1. In blasting, to plug up with clay, earth, dry sand, sod,
      or other material, as a hole bored in a rock, in order to
      prevent the force of the explosion from being misdirected.
      [1913 Webster]

   2. To drive in or down by frequent gentle strokes; as, to
      tamp earth so as to make a smooth place.
      [1913 Webster]

WordNet (r) 3.0 (2006):

tamp
    n 1: a tool for tamping (e.g., for tamping tobacco into a pipe
         bowl or a charge into a drill hole etc.) [syn: tamp,
         tamper, tamping bar]
    v 1: press down tightly; "tamp the coffee grinds in the
         container to make espresso" [syn: tamp down, tamp,
         pack]

Moby Thesaurus II by Grady Ward, 1.0:

87 Moby Thesaurus words for "tamp":
   assault, bear, bear upon, boost, buck, bull, bulldoze, bump,
   bump against, bunt, butt, butt against, concentrate, cram, cram in,
   crowd, crowd in, dent, depress, dig, dimple, dint, drive, drive in,
   elbow, engrave, fill up, force, force in, goad, hurtle, hustle,
   impact, impress, imprint, indent, jab, jam, jam in, jam-pack, jog,
   joggle, jolt, jostle, knock in, notch, nudge, pack in, pang,
   pile drive, pit, plug up, plunge in, pock, pockmark, poke, poke in,
   pound in, press, press in, prod, punch, punch in, push, push in,
   ram, ram down, ram in, rattle, recess, run, run against, run in,
   set back, set in, shake, shoulder, shove, squeeze in, stamp,
   stress, stuff, stuff in, tamp in, thrust, thrust in, wedge in