The Collaborative International Dictionary of English v.0.48:

Glucose \Glu"cose`\, n. [Gr. ? sweet. Cf. Glycerin.]
   [1913 Webster]
   1. A variety of sugar occurring in nature very abundantly, as
      in ripe grapes, and in honey, and produced in great
      quantities from starch, etc., by the action of heat and
      acids. It is only about half as sweet as cane sugar.
      Called also dextrose, grape sugar, diabetic sugar,
      and starch sugar. See Dextrose.
      [1913 Webster]

   2. (Chem.) Any one of a large class of sugars, isometric with
      glucose proper, and including levulose, galactose, etc.
      [1913 Webster]

   3. The trade name of a sirup, obtained as an uncrystallizable
      reside in the manufacture of glucose proper, and
      containing, in addition to some dextrose or glucose, also
      maltose, dextrin, etc. It is used as a cheap adulterant of
      sirups, beers, etc.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Dextrose \Dex"trose`\ (d[e^]ks"tr[=o]s`), n. [See Dexter.]
   (Chem.)
   A sirupy, or white crystalline, variety of sugar, C6H12O6
   (so called from turning the plane of polarization to the
   right), occurring in many ripe fruits, and also called
   glucose. Dextrose and levulose are obtained by the
   inversion of cane sugar or sucrose, and hence the mixture is
   called called invert sugar. Dextrose is chiefly obtained by
   the action of heat and acids on starch, and hence called also
   starch sugar. It is also formed from starchy food by the
   action of the amylolytic ferments of saliva and pancreatic
   juice.
   [1913 Webster]

   Note: The solid products are known to the trade as grape
         sugar; the sirupy products as glucose, or mixing
         sirup. These are harmless, but are only about half as
         sweet as cane sugar or sucrose. Dextrously
         Dextrous

WordNet (r) 3.0 (2006):

glucose
    n 1: a monosaccharide sugar that has several forms; an important
         source of physiological energy