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.

A complex sugar, as raffinose, yielding by hydrolysis three simple sugar molecules.