"small vessel for holding salt, used on the table," mid-15c., a redundant formation from salt (n.) + saler "salt-cellar" (mid-14c.), from Old French salier "salt box" (Modern French salière) and Medieval Latin salare, 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 etymological connection between saler and "salt" was lost, a redundant salt- was tacked on to the beginning of the word; the second element was influenced by Old French sel "salt" and by unrelated English cellar.
"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).
The meaning "racy, sexy" is from 1866, from salt in the sense of "that which gives life or pungency" (1570s, originally in reference to words or wit); salt (adj.) also was used of lecherous (female) dogs, etc. (1540s) and also of persons (16c.-17c.).
The U.S. slang sense of "angry, irritated" is first attested 1938 (perhaps from similar use with regard to sailors, "tough, aggressive," which is attested by 1920), especially in phrase jump salty "unexpectedly become enraged" (1938). Related: Saltily.
Proto-Indo-European root meaning "salt."
It is the hypothetical source of/evidence for its existence is provided by: Greek hals "salt, sea;" Latin sal, Old Church Slavonic soli, Old Irish salann, Welsh halen, Old English sealt, German Salz "salt."
late 13c., ile, from Old French ile, earlier isle, from Latin insula "island," a word of uncertain origin.
Perhaps (as the Ancients guessed) from in salo "(that which is) in the (salty) sea," from ablative of salum "the open sea," related to sal "salt" (see salt (n.)). De Vaan finds this "theoretically possible as far as the phonetics go, but being 'in the sea' is not a very precise description of what an island is; furthermore, the Indo-Europeans seem to have indicated with 'island' mainly 'river islands.' ... Since no other etymology is obvious, it may well be a loanword from an unknown language." He proposes the same lost word as the source of Old Irish inis, Welsh ynys "island" and Greek nēsos "island." The -s- was restored first in French, then in English in the late 1500s.
"potassium nitrate," a chief constituent of gunpowder, c. 1500, earlier salpetre (early 14c.), from Old French salpetre, from Medieval Latin sal petrae "salt of rock," from Latin sal "salt" (from PIE root *sal- "salt") + petra "rock, stone" (see petrous). So called because it looks like salt encrusted on rock and has a saline taste. Spelling was conformed to salt. Related: Saltpetrous.