The Collaborative International Dictionary of English v.0.48:

blacktop \blacktop\ n.
   1. a bituminous material used for providing a smooth paving
      to a road.
      [PJC]

   2. the surface of a road paved with blacktop[1].
      [PJC]

WordNet (r) 3.0 (2006):

blacktop
    n 1: a black bituminous material used for paving roads or other
         areas; usually spread over crushed rock [syn: blacktop,
         blacktopping]
    v 1: coat with blacktop; "blacktop the driveway"

Moby Thesaurus II by Grady Ward, 1.0:

37 Moby Thesaurus words for "blacktop":
   Tarmac, Tarvia, asphalt, bitumen, bituminous macadam, brick,
   carpet, causeway, cement, cobble, cobblestone, concrete, curb,
   curbing, curbstone, edgestone, flag, flagging, flagstone, floor,
   gravel, kerb, kerbstone, macadam, metal, pave, pavement, pavestone,
   paving, paving stone, pebble, road metal, stone, tar, tarmacadam,
   tile, washboard