The Collaborative International Dictionary of English v.0.48:

Asphalt \As"phalt\, Asphaltum \As*phal"tum\, n. [Gr. ?, of
   eastern origin: cf. F. asphalte.]
   1. Mineral pitch, Jews' pitch, or compact native bitumen. It
      is brittle, of a black or brown color and high luster on a
      surface of fracture; it melts and burns when heated,
      leaving no residue. It occurs on the surface and shores of
      the Dead Sea, which is therefore called Asphaltites, or
      the Asphaltic Lake. It is found also in many parts of
      Asia, Europe, and America. See Bitumen.
      [1913 Webster]

   2. A composition of bitumen, pitch, lime, and gravel, used
      for forming pavements, and as a water-proof cement for
      bridges, roofs, etc.; asphaltic cement. Artificial asphalt
      is prepared from coal tar, lime, sand, etc.
      [1913 Webster]

   Asphalt stone, Asphalt rock, a limestone found
      impregnated with asphalt.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Asphalt \As"phalt\, v. t.
   To cover with asphalt; as, to asphalt a roof; asphalted
   streets.
   [1913 Webster]

WordNet (r) 3.0 (2006):

asphalt
    n 1: mixed asphalt and crushed gravel or sand; used especially
         for paving but also for roofing
    2: a dark bituminous substance found in natural beds and as
       residue from petroleum distillation; consists mainly of
       hydrocarbons [syn: asphalt, mineral pitch]
    v 1: cover with tar or asphalt; "asphalt the driveway"

Moby Thesaurus II by Grady Ward, 1.0:

154 Moby Thesaurus words for "asphalt":
   Formica, Masonite, Tarmac, Tarvia, alabaster, amphibole, antimony,
   apatite, aplite, arsenic, asbestos, azurite, bauxite, bitumen,
   bituminous macadam, blacktop, boron, brick, brimstone, bromine,
   brucite, calcite, canvas, carbon, carpeting, celestite, cement,
   chalcedony, chlorite, chromite, clapboard, clay, coal, cobble,
   cobblestone, coke, concrete, cork tile, corundum, cryolite, curb,
   curbing, curbstone, diatomite, edgestone, emery, epidote, epsomite,
   feldspar, fiber glass, flag, flagging, flagstone, flooring, garnet,
   glauconite, graphite, gravel, gypsum, hatchettine, holosiderite,
   iron pyrites, jet, kerb, kerbstone, kyanite, lignite, lime,
   linoleum, macadam, magnesite, malachite, maltha, marcasite, marl,
   meerschaum, mica, mineral coal, mineral oil, mineral salt,
   mineral tallow, mineral tar, mineral wax, molybdenite, monazite,
   obsidian, olivine, ozokerite, pantile, paper, parquet, pavement,
   pavestone, paving, paving stone, peat, perlite, phosphate rock,
   phosphorus, plasterboard, plywood, pumice, pyrite, pyrites,
   pyroxene, quartz, realgar, red clay, rhodonite, road metal,
   rock crystal, rocks, roofage, roofing, roofing paper, salt,
   selenite, selenium, shake, sheathing board, sheeting, shingle,
   siderite, siding, silica, silicate, silicon, slate, spar, spinel,
   spodumene, spun glass, stone, sulfur, talc, talcum, tar paper,
   tarmacadam, tellurium, thatch, tile, tilestone, tiling, veneer,
   wainscoting, wallboard, walling, wallpaper, washboard,
   weatherboard, wollastonite, wood, wulfenite, zeolite