(transitive) To add sugar to; to sweeten with sugar.
(transitive) To make (something unpleasant) seem less so.
(US, Canada, regional) In making maple sugar, to complete the process of boiling down the syrup till it is thick enough to crystallize; to approach or reach the state of granulation; with the preposition off.
(entomology) To apply sugar to trees or plants in order to catch moths.