- a brown algae (genus Sargassum) with berrylike air sacs, found floating in the Gulf Stream, Pacific Ocean, etc.
See gulfweed in American Heritage Dictionary 4
also gulf weed noun
Any of several brownish seaweeds of the genus Sargassum of tropical Atlantic waters, having rounded air bladders and often forming dense, floating masses. Also called sargasso, sargassum.
Origin: After the Gulf of Mexico