sargasso
A brown alga, of the genus Sargassum, that forms large, floating masses.
countable, uncountable
SARGASSO, the Sea-Lentile.
Also Sargasso: a confused, tangled mass or situation.
countable, figuratively, uncountable
Afghanistan is a sargasso of wrecks from earlier civilizations; buried in its earth are hordes of Greek coins, Aramaic inscriptions, Saljuq mosques, and Mazdakite fire temples, flaking away in their own dust, forgotten in valleys where the local villagers carry away their bricks for cattle folds.
A part of an ocean or sea characterized by floating masses of sargassos, like the Sargasso Sea.
countable, uncountable
Of Sargassos or Weedy Seas. [...] [T]he most remarkable of them all, is that in the North Atlantic. [Christopher] Columbus passed through it on his first voyage of discovery to America. […] The sargassos of the southern hemisphere are not so well marked as this, nor are they as rich in drift or floating matter.
Where it comes from
From Portuguese sargaço (“(originally) the Lisbon false sun-rose or woolly rock rose (Halimium lasianthum); (now) gulfweed, sargasso”), ultimately from Latin salicastrum (“kind of wild vine found in willow-thickets”), from salix (“plant of the genus Salix; willow”) + -astrum (suffix forming nouns expressing incomplete resemblance). Salix is derived from Proto-Indo-European *sl̥H-ik- (“willow”). The English word is cognate with French sargasse, Spanish sargazo. The capitalized form of sense 2 (“a confused, tangled mass or situation”), Sargasso, is probably a reference to the Sargasso Sea.
Adapted from the Wiktionary entry sargasso (CC BY-SA 4.0).