Any one of a group of compounds consisting of a pyranose sugar residue, such as glucose, linked to a noncarbohydrate residue (R) by a glycosidic bond: the hydroxyl group (–OH) on carbon-1 of the sugar is replaced by –OR. Glycosides are widely distributed in plants; examples are the anthocyanin pigments and the cardiac glycosides, such as digoxin and ouabain, which are used medicinally for their stimulant effects on the heart.