"a tidal river," 1650s; see salt (n. ) + river. as a proper name, it was used early 19c. with reference to backwoods inhabitants of the U.S., especially those of Kentucky (there is a Salt River in the Bluegrass region of the state; the river is not salty, but salt manufactured from salt licks in the area was shipped down the river). The U.S. political slang phrase to row (someone) up Salt River "send (someone) to political defeat" probably owes its origin to this geographical reference, as the first attested use (1828) is in a Kentucky context. The phrase may also refer to the salt of tears.
"the sea; naturally occurring salt water," late Old English sealtera watera. As an adjective from 1520s, "inhabiting salt water or the sea." Salt-water taffy attested by 1886; so called because it originally was sold at seashore resorts, especially Atlantic City, N.J. (see taffy).
lake of the River Jordan, mid-13c., from dead (adj.); its water is 26 percent salt (as opposed to 3 or 4 percent in most oceans) and supports practically no life. In the Bible it was the "Salt Sea" (Hebrew yam hammelah), also "Sea of the Plain" and "East Sea." In Arabic it is al-bahr al-mayyit "Dead Sea." The ancient Greeks knew it as he Thalassa asphaltites "the Asphaltite Sea." Latin Mare Mortum, Greek he nekra thalassa (both "The Dead Sea") referred to the sea at the northern boundaries of Europe, the Arctic Ocean.