1. A monosaccharide sugar, 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. Also called D-glucose. 2. 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. Also called starch syrup.