sargasso (n.) Look up sargasso at
"seaweed," 1590s, from Portuguese sargasso "seaweed," perhaps from sarga, a type of grape (on this theory, the sea plant was so called from its berry-like air sacs), or from Latin sargus, a kind of fish found in the Mediterranean and eastern Atlantic, from Greek sargos. Sargasso Sea attested from 1819.