WordNet (r) 3.0 (2006):

sandbar
    n 1: a bar of sand [syn: sandbar, sand bar]

Moby Thesaurus II by Grady Ward, 1.0:

45 Moby Thesaurus words for "sandbar":
   ait, archipelago, atoll, bank, bar, cay, continental island,
   coral head, coral heads, coral island, coral reef, flat, ford,
   holm, insularity, ironbound coast, island, island group,
   islandology, isle, islet, key, ledges, lee shore, oceanic island,
   pitfall, quicksands, reef, rockbound coast, rocks, sand, sand dune,
   sand pile, sandbank, sands, shallow, shallows, shelf, shoal,
   shoal water, shoals, tidal flats, undercurrent, undertow,
   wetlands