- a brown algae (genus Sargassum) with berrylike air sacs, found floating in the Gulf Stream, Pacific Ocean, etc.
also gulf weed
Any of several brownish seaweeds of the genus Sargassum having rounded air bladders and often forming dense, floating masses in the Atlantic Ocean. Also called sargasso, sargassum.
Origin of gulfweedAfter the Gulf of Mexico.
(usually uncountable, plural gulfweeds)