gulfweed

from WordNet (r) 3.0 (2006)

gulfweed
    n 1: brown algae with rounded bladders forming dense floating
         masses in tropical Atlantic waters as in the Sargasso Sea
         [syn: {gulfweed}, {sargassum}, {sargasso}, {Sargassum
         bacciferum}]

from The Collaborative International Dictionary of English v.0.48

gulfweed \gulf"weed`\ (g[u^]lf"w[=e]d`), n.
   1. A brown seaweed ({Sargassum bacciferum}) with rounded
      bladders forming dense floating masses in tropical
      Atlantic waters as in the Sargasso Sea.

   Syn: sargassum, sargasso, {Sargassum bacciferum}.
        [WordNet 1.5]