salt-cellar (n.)

"small vessel for holding salt, used on the table," mid-15c., from salt (n.) + saler "salt-cellar" (14c.), from Old French salier "salt box" (Modern French salière), from Latin salarium, noun use of adjective meaning "pertaining to salt," from a diminutive of Latin sal "salt" (from PIE root *sal- "salt").

As the connection between *saler and "salt" was lost, a redundant salt- was tacked on to the beginning of the word; the second element has been altered on model of unrelated cellar.