sargasso
noun
sar·gas·so sär-ˈga-(ˌ)sō 
plural sargassos
1
: gulfweed, sargassum
2
: a mass of floating vegetation and especially sargassums
Example Sentences
Recent Examples on the Web Like the rest of the Caribbean, Tulum sometimes suffers from the scourge of sargasso seaweed. 
Jamie Ditaranto, Travel + Leisure, 5 Aug. 2021
Jamie Ditaranto, Travel + Leisure, 5 Aug. 2021 Word History
Etymology
borrowed from Portuguese sargaço, apparently the same word as sargaço, sargaça "the flowering plant Halimium lasianthum, related to the rockrose," of uncertain origin
Note: Traced by Coromines (Diccionario crítico etimológico castellano e hispánico) along with Spanish jaguarzo to a putative Mozarabic *xaugaçro, going back to Latin salicastrum, a plant of uncertain identity named by Pliny.
First Known Use
1598, in the meaning defined at sense 1