The noun sugar has 3 senses (first 1 from tagged texts)
1. (41) sugar, refined sugar -- (a white crystalline carbohydrate used as a sweetener and preservative)
2. carbohydrate, saccharide, sugar -- (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)