glucose

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A monosaccharide sugar, C₆H₁₂O₆, occurring widely in most plant and animal tissue. It is the principal circulating sugar in the blood and the major energy source of the body.
• noun A colorless to yellowish syrupy mixture of dextrose, maltose, and dextrins containing about 20 percent water, used in confectionery, alcoholic fermentation, tanning, and treating tobacco.

from The Century Dictionary.

• noun The name of a group of sugars having the formula. C₆H₁₂O₆, which may be regarded as aldehydes of hexatomic alcohols.
• noun In com., the sugar-syrup obtained by the conversion of starch into sugar by sulphuric acid, the solid product being called grape-sugar, starch-sugar, diabetic sugar, etc.

from the GNU version of the Collaborative International Dictionary of English.

• noun 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.
• noun (Chem.) Any one of a large class of sugars, isometric with glucose proper, and including levulose, galactose, etc.
• noun 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.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun biochemistry A simple monosaccharide (sugar) with a molecular formula of C6H12O6; it is a principle source of energy for cellular metabolism.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a monosaccharide sugar that has several forms; an important source of physiological energy