1) The chemical or biochemical addition of carbohydrate or glycosyl groups to other chemicals, especially peptides or proteins. Glycosyl transferases are used in this biochemical reaction.

2) Chemical or biochemical addition of carbohydrate or glycosyl groups to other chemicals, especially peptides or proteins.

3) The covalent attachment of a glycosyl residue to a substrate molecule. (GOC:mah)

4) The covalent chemical or biochemical addition of carbohydrate or glycosyl groups to other chemicals, by glycosyl transferases.