Английский Этимологический словарь - salt

- O.E. sealt, from P.Gmc. *saltan, from PIE *sal-. Meaning "sailor" is first attested 1840. Many metaphoric uses reflect that this was once a rare and important resource, cf. worth one's salt, salt of the earth (Matt. v:13). To take something with a grain of salt is from 17c. Saltpeter is 14c., from O.Fr. salpetre, from M.L. sal petrae "salt of rock," so called because it looks like salt encrusted on rock. Saltcellar (late M.E.) is a redundancy, the -cellar being originally Anglo-Norm. *saler (14c.), the original name for the thing, from a dim. of L. sal "salt." As the connection between this word and "salt" was lost, salt- was tacked on to the beginning.