1. [n]  a white crystalline carbohydrate used as a sweetener and preservative
2. [n]  an essential structural component of living cells and source of energy for animals; includes simple sugars with small molecules as well as macromolecular substances; are classified according to the number of monosaccharide groups they contain
3. [v]  sweeten with sugar; "sugar your tea"

1. \Sug"ar\, n. [OE. sugre, F. sucre (cf. It. zucchero, Sp.
   az['u]car), fr. Ar. sukkar, assukkar, fr. Skr. [,c]arkar[=a]
   sugar, gravel; cf. Per. shakar. Cf. {Saccharine}, {Sucrose}.]
   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}, or {Diabetic}, {sugar} (Med. Chem.), a variety of
      sugar (probably grape sugar or dextrose) excreted in the
      urine in diabetes mellitus.
   {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} (Zo["o]l.), any one of several species of small
      South American singing birds of the genera {C[oe]reba},
      {Dacnis}, and allied genera belonging to the family
      {C[oe]rebid[ae]}. 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}. (Zo["o]l.)
      (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} (Zo["o]l.), 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.
   

2. \Sug"ar\, v. i.
   In making maple sugar, to complete the process of boiling
   down the sirup till it is thick enough to crystallize; to
   approach or reach the state of granulation; -- with the
   preposition off. [Local, U.S.]
   

3. \Sug"ar\, v. t. [imp. & p. p. {Sugared}; p. pr. & vb. n.
   {Sugaring}.]
   1. To impregnate, season, cover, or sprinkle with sugar; to
      mix sugar with. ``When I sugar my liquor.'' --G. Eliot.
   2. To cover with soft words; to disguise by flattery; to
      compliment; to sweeten; as, to sugar reproof.
            With devotion's visage And pious action we do sugar
            o'er The devil himself.               --Shak.
   

A simple lazy functional language designed at Westfield College, University of London, UK and used in Principles of Functional Programming, Hugh Glaser et al, P-H 1984.