According to google:-
sugar definition chemistry
As a chemical term, “sugar” usually refers to all carbohydrates of the general formula C n(H 2O) n. Sucrose is a disaccharide, or double sugar, being composed of one molecule of glucose linked to one molecule of fructose.
sugar definition biology
noun, plural: sugars. (1) Any monosaccharide or disaccharide, used especially by organisms to store energy. (2) Any sweet, crystalline solid disaccharide used as sweetener or preservative. Supplement. The term sugar is the generic term for any disachharides (e.g. sucrose) and monosaccharides (e.g. fructose, glucose).
sugar definition nutrition
Sugars are a type of simple carbohydrate. They have a sweet taste. Sugars can be found naturally in fruits, vegetables, milk, and milk products. They are also added to many foods and drinks during preparation or processing. Types of sugar include glucose, fructose, and sucrose.