a sugar (like sucrose or fructose) that does not hydrolyse to give other sugars; the simplest group of carbohydrates

a monosaccharide sugar having six carbon atoms and an aldehyde group

Any aldose having three carbon atoms; in reality, just glyceraldehyde.

a monosaccharide with five carbon atoms, one of which is an aldehyde group; for example, ribose.

A four-carbon aldose; for example, threose, erythrose.