A simple sugar; any of a number of sugars (including the trioses, tetroses, pentoses, hexoses, etc.), not decomposable into simpler sugars by hydrolysis. Specif., as used by some, a hexose. The monosaccharides are all open-chain compounds containing hydroxyl groups and either an aldehyde group or a ketone group.
- Any of several carbohydrates, such as tetroses, pentoses, and hexoses, that cannot be broken down to simpler sugars by hydrolysis. Also called simple sugar.