lac·tose n.
 1. Physiol. Chem. The main sugar present in milk, called also sugar of milk or milk sugar.  When isolated pure it is obtained crystalline; it is separable from the whey by evaporation and crystallization.  It is a disaccharide with the formula C12H22O11, being chemically 4-(β-D-galactosido)-D-glucose. It has a slightly sweet taste, is dextrorotary, and is much less soluble in water than either cane sugar or glucose. Formerly called lactin.  When hydrolyzed it yields glucose and galactose.  In cells it may be hydrolyzed by the enzyme β-galactosidase.
 2. Chem. See Galactose.

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 Milk n.
 1. Physiol. A white fluid secreted by the mammary glands of female mammals for the nourishment of their young, consisting of minute globules of fat suspended in a solution of casein, albumin, milk sugar, and inorganic salts. “White as morne milk.”
 2. Bot. A kind of juice or sap, usually white in color, found in certain plants; latex. See Latex.
 3. An emulsion made by bruising seeds; as, the milk of almonds, produced by pounding almonds with sugar and water.
 4. Zool. The ripe, undischarged spat of an oyster.
 Condensed milk. See under Condense, v. t.
 Milk crust Med., vesicular eczema occurring on the face and scalp of nursing infants. See Eczema.
 Milk fever. (a) Med. A fever which accompanies or precedes the first lactation. It is usually transitory. (b) Vet. Surg. A form puerperal peritonitis in cattle; also, a variety of meningitis occurring in cows after calving.
 Milk glass, glass having a milky appearance.
 Milk knot Med., a hard lump forming in the breast of a nursing woman, due to obstruction to the flow of milk and congestion of the mammary glands.
 Milk leg Med., a swollen condition of the leg, usually in puerperal women, caused by an inflammation of veins, and characterized by a white appearance occasioned by an accumulation of serum and sometimes of pus in the cellular tissue.
 Milk meats, food made from milk, as butter and cheese. [Obs.] --Bailey.
 Milk mirror. Same as Escutcheon, 2.
 Milk molar Anat., one of the deciduous molar teeth which are shed and replaced by the premolars.
 Milk of lime Chem., a watery emulsion of calcium hydrate, produced by macerating quicklime in water.
 Milk parsley Bot., an umbelliferous plant (Peucedanum palustre) of Europe and Asia, having a milky juice.
 Milk pea Bot., a genus (Galactia) of leguminous and, usually, twining plants.
 Milk sickness Med., See milk sickness in the vocabulary.
 Milk snake Zool., a harmless American snake (Ophibolus triangulus, or Ophibolus eximius). It is variously marked with white, gray, and red.  Called also milk adder, chicken snake, house snake, etc.
 Milk sugar. Physiol. Chem. See Lactose, and Sugar of milk (below).
 Milk thistle Bot., an esculent European thistle (Silybum marianum), having the veins of its leaves of a milky whiteness.
 Milk thrush. Med. See Thrush.
 Milk tooth Anat., one of the temporary first set of teeth in young mammals; in man there are twenty.
 Milk tree Bot., a tree yielding a milky juice, as the cow tree of South America (Brosimum Galactodendron), and the Euphorbia balsamifera of the Canaries, the milk of both of which is wholesome food.
 Milk vessel Bot., a special cell in the inner bark of a plant, or a series of cells, in which the milky juice is contained. See Latex.
 Rock milk. See Agaric mineral, under Agaric.
 Sugar of milk. The sugar characteristic of milk; a hard white crystalline slightly sweet substance obtained by evaporation of the whey of milk.  It is used in pellets and powder as a vehicle for homeopathic medicines, and as an article of diet. See Lactose.


 Sug·ar n.
 1. A sweet white (or brownish yellow) crystalline substance, of a sandy or granular consistency, obtained by crystallizing the evaporated juice of certain plants, as the sugar cane, sorghum, beet root, sugar maple, etc. It is used for seasoning and preserving many kinds of food and drink. Ordinary sugar is essentially sucrose. See the Note below.
 Note: ☞ The term sugar includes several commercial grades, as the white or refined, granulated, loaf or lump, and the raw brown or muscovado. In a more general sense, it includes several distinct chemical compounds, as the glucoses, or grape sugars (including glucose proper, dextrose, and levulose), and the sucroses, or true sugars (as cane sugar). All sugars are carbohydrates. See Carbohydrate.
     The glucoses, or grape sugars, are ketone alcohols of the formula C6H12O6, and they turn the plane of polarization to the right or the left. They are produced from the amyloses and sucroses, as by the action of heat and acids of ferments, and are themselves decomposed by fermentation into alcohol and carbon dioxide. The only sugar (called acrose) as yet produced artificially belongs to this class. The sucroses, or cane sugars, are doubled glucose anhydrides of the formula C12H22O11. They are usually not fermentable as such (cf. Sucrose), and they act on polarized light.
 2. By extension, anything resembling sugar in taste or appearance; as, sugar of lead (lead acetate), a poisonous white crystalline substance having a sweet taste.
 3. Compliment or flattery used to disguise or render acceptable something obnoxious; honeyed or soothing words. [Colloq.]
 Acorn sugar. See Quercite.
 Cane sugar, sugar made from the sugar cane; sucrose, or an isomeric sugar. See Sucrose.
 Diabetes sugar, or Diabetic sugar Med. Chem., a variety of sugar (grape sugar or dextrose) excreted in the urine in diabetes mellitus; -- the presence of such a sugar in the urine is used to diagnose the illness.
 Fruit sugar. See under Fruit, and Fructose.
 Grape sugar, a sirupy or white crystalline sugar (dextrose or glucose) found as a characteristic ingredient of ripe grapes, and also produced from many other sources. See Dextrose, and Glucose.
 Invert sugar. See under Invert.
 Malt sugar, a variety of sugar isomeric with sucrose, found in malt. See Maltose.
 Manna sugar, a substance found in manna, resembling, but distinct from, the sugars. See Mannite.
 Milk sugar, a variety of sugar characteristic of fresh milk, and isomeric with sucrose. See Lactose.
 Muscle sugar, a sweet white crystalline substance isomeric with, and formerly regarded to, the glucoses.  It is found in the tissue of muscle, the heart, liver, etc. Called also heart sugar. See Inosite.
 Pine sugar. See Pinite.
 Starch sugar Com. Chem., a variety of dextrose made by the action of heat and acids on starch from corn, potatoes, etc.; -- called also potato sugar, corn sugar, and, inaccurately, invert sugar. See Dextrose, and Glucose.
 Sugar barek, one who refines sugar.
 Sugar beet Bot., a variety of beet (Beta vulgaris) with very large white roots, extensively grown, esp. in Europe, for the sugar obtained from them.
 Sugar berry Bot., the hackberry.
 Sugar bird Zool., any one of several species of small South American singing birds of the genera Coereba, Dacnis, and allied genera belonging to the family Coerebidae. They are allied to the honey eaters.
 Sugar bush. See Sugar orchard.
 Sugar camp, a place in or near a sugar orchard, where maple sugar is made.
 Sugar candian, sugar candy. [Obs.]
 Sugar candy, sugar clarified and concreted or crystallized; candy made from sugar.
 Sugar cane Bot., a tall perennial grass (Saccharum officinarium), with thick short-jointed stems. It has been cultivated for ages as the principal source of sugar.
 Sugar loaf. (a) A loaf or mass of refined sugar, usually in the form of a truncated cone. (b) A hat shaped like a sugar loaf.
    Why, do not or know you, grannam, and that sugar loaf?   --J. Webster.
 -- Sugar maple Bot., the rock maple (Acer saccharinum). See Maple.
 Sugar mill, a machine for pressing out the juice of the sugar cane, usually consisting of three or more rollers, between which the cane is passed.
 Sugar mite. Zool. (a) A small mite (Tyroglyphus sacchari), often found in great numbers in unrefined sugar. (b) The lepisma.
 Sugar of lead. See Sugar, 2, above.
 Sugar of milk. See under Milk.
 Sugar orchard, a collection of maple trees selected and preserved for purpose of obtaining sugar from them; -- called also, sometimes, sugar bush. [U.S.] --Bartlett.
 Sugar pine Bot., an immense coniferous tree (Pinus Lambertiana) of California and Oregon, furnishing a soft and easily worked timber. The resinous exudation from the stumps, etc., has a sweetish taste, and has been used as a substitute for sugar.
 Sugar squirrel Zool., an Australian flying phalanger (Belideus sciureus), having a long bushy tail and a large parachute. It resembles a flying squirrel. See Illust. under Phlanger.
 Sugar tongs, small tongs, as of silver, used at table for taking lumps of sugar from a sugar bowl.
 Sugar tree. Bot. See Sugar maple, above.