The Collaborative International Dictionary of English v.0.48:

Cobblestone \Cob"ble*stone`\, n.
   A large pebble; a rounded stone not too large to be handled;
   a small boulder; -- used for paving streets and for other
   purposes.
   [1913 Webster]

WordNet (r) 3.0 (2006):

cobblestone
    n 1: rectangular paving stone with curved top; once used to make
         roads [syn: cobble, cobblestone, sett]
    v 1: pave with cobblestones [syn: cobble, cobblestone]

Moby Thesaurus II by Grady Ward, 1.0:

37 Moby Thesaurus words for "cobblestone":
   Tarmac, Tarvia, asphalt, bitumen, bituminous macadam, blacktop,
   brick, carpet, causeway, cement, cobble, 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