a. A substance, known chemically as sodium chloride (NaCl), very abundant in nature both in solution and in crystalline form, and extensively prepared for use as a condiment, a preservative of animal food, and in various industrial processes. Salt for domestic use is manufactured from sea salt n. ( marine-salt, bay-salt n.), rock salt n. ( mineral salt, †salt mineral), and (now chiefly) from brine pumped up from rock-salt strata. Frequently called common salt.

b. With qualifying word. white salt: salt prepared and refined mainly for household use (as contrasted with rock-salt, which is of a brownish red colour). †great salt: salt in large crystals or lumps; rock-salt. †small salt: salt powdered as for table use. †Pattow salt, †Pateu salt [i.e. Poitou salt = French ‘sel de Poictou, blacke salt, gray salt’ Cotgrave] : ? a coarse kind of salt manufactured in Poitou. Also Newcastle salt, Spanish salt.

†c. salt upon salt: see quot. 1748. Obsolete.

d. in salt: sprinkled with salt or immersed in brine; in pickle.

e. spirit of salt (cf. spirit n. 23a).

a. gen.

b. Taken as a type of a necessary adjunct to food, and hence as a symbol of hospitality. to eat salt with (a person), to eat (a person's) salt: to enjoy his hospitality; also occasionally to be dependent upon him. bread and salt: see bread and salt n. at bread n. Phrases 2d.

c. In allusions to the jocular advice given to children to catch birds by putting salt on their tails.

d. with a grain of salt [= modern Latin cum grano salis] : (to accept a statement) with a certain amount of reserve. Also in similar phrases, now esp. with a pinch of salt.

e. With reference to the bitter saline taste of tears.

f. not to be made of sugar or salt: not to be readily affected by moisture; hence, not to be disconcerted by wet weather.

g. (to be) worth one's salt: efficient or capable. Usually with expressed or implied negative.

h. With reference to the saltness of the sea, in phrases denoting fondness for or adaptability to a seafaring life. (Cf. 11.)

i. to rub salt in one's wounds: to behave or speak to someone so as to aggravate a hurt already inflicted.

a. (the) salt of the earth (after Matthew v. 13): the excellent of the earth; formerly, in trivial use, the powerful, aristocratic, or wealthy; now also applied to a person or persons of great worthiness, reliability, honesty, etc.

b. That which gives liveliness, freshness, or piquancy to a person's character, life, etc. Often in salt of youth, from Shakespeare.

c. That which gives life or pungency to discourse or written composition; poignancy of expression; pungent wit; †point. Attic salt: see Attic adj. 2.

†a. A solid soluble non-inflammable substance having a taste. Obsolete.The name originally comprised such substances as resembled common salt (sense 1) in their appearance or properties, e.g. substances produced by the evaporation of watery liquids as salt is produced by the evaporation of sea-water. The quality of the taste was not originally considered to be a criterion of the class, but was added in the 18th cent., when these substances were ultimately divided into ‘acid salts’ (salia acida), ‘alkaline salts’ (salia alkalina), and ‘neutral salts’ (salia neutra, media, or salsa), corresponding to the modern ‘acids’, ‘alkalis’, and ‘salts’.

b. Particular substances of this class are distinguished by defining words (cf. sal n.¹); e.g. †salt ammoniac (= sal ammoniac n.), †essential salt, †fixed salt, †salt perlate, †salt sedative, volatile salt; †salt of antimony, †salt of Saturn, salt of soda, †salt of steel, †salt of wisdom; †salt anatron, †salt gem(me (= sal-gem n.), †salt prunel(la (= sal-prunella n.), †salt nitre (= sal-nitre n.), †salt sode (= sal-soda), †salt tartar; Glauber's salt n., Rochelle salt, etc. salt of lemon, potassium hydrogen oxalate, used to remove ink-stains and iron-mould from linen; †salt of Mars, ferrous sulphate (obsolete). Carlsbad salts (or Karlsbad salts), Vichy salts, salts prepared from the mineral springs in these places, or imitations of them; Everitt's salt (see quot. 1939); Monsel's salts (see quot. 1890²); †Preston salts, a variety of smelling-salts.

a. Modern Chemistry. A compound formed by the union of an acid radical with a basic radical; an acid having the whole or part of its hydrogen replaced by a metal. (In wider theoretical use the term ‘salt’ includes acids as salts of hydrogen.) Also, †ethereal salt, an ester.The first marked step towards the modern conception of a chemical salt was Rouelle's definition (a1770) of a neutral salt as a compound formed by the union of an acid with any substance serving as a base for it and giving to it a concrete or solid form. Various modifications of this or earlier views were put forward until the publication of Lavoisier's definition of a salt as the union of an acid with an oxide; this definition, however, was found to be inadequate when the composition of the halogen compounds, sulphides, etc. came to be accurately known. A further revolution in the theory of salts was made by Berzelius, who divided them into two classes; viz. haloid adj. and n. salts, formed of an electropositive element and a halogen, and amphide adj. salts, resulting from the union of an acid and a base; the latter he subdivided into oxy-salts, sulpho-salts, selenio-salts, and telluri-salts. According to more recent conceptions (Arrhenius 1888) salts, including acids, are regarded as composed of positive ions or cations (hydrogen and metals) and negative ions or anions (halogens and acid radicals).

b. metallic salt, a salt of which the basic component is an oxide or hydroxide of a metallic element.

a. = salt cellar n.

b. above (or below, beneath, under) the salt: at the upper (or lower) part of the table, i.e. among the more honoured (or less honoured) guests.The reference is to the formerly prevailing custom of placing a large salt cellar in the middle of a dining table.

a. Of water, brine-springs, etc. salt finger, one of a number of alternating columns of rising and descending water produced when a layer of water is overlain by a denser, more salty layer; so salt fingering, the occurrence of salt fingers; salt spray, used attributively to denote a test in which an article is subjected to a spray of salt water, and the associated apparatus. See also salt spring n., salt water n. and adj.In Middle English poetry salt sea, salt flood (now occasionally archaic), salt foam, salt stream are frequent phrases for the sea.

b. Applied to tears; †also, to humours, etc.See also salt rheum n.

c. Of tracts of land, marshes: Flooded by the sea. (See also salt marsh n.) Of rocks, ground: Having salt mixed with the earth; (in biblical use) barren. salt flat, a flat expanse of land covered with a layer of salt; salt meadow (chiefly North American), a meadow liable to be flooded by salt water.