-_səm noun
Etymology: New Latin, from International Scientific Vocabulary sargasso
1. capitalized : a genus of brown algae that have branching thalli with lateral outgrowths differentiated as leafy segments, air bladders, or spore-bearing structures, that develop initially along tropical shores from which they break away to drift in the open ocean (as the Sargasso sea) and reproduce vegetatively for indefinite periods, and that are usually placed in the family Fucaceae but are sometimes isolated in a separate family — see gulfweed
2. -s : any plant of the genus Sargassum