Illustrated Glossary of Organic Chemistry

Carbohydrate (saccharide): A contraction of carbon hydrate. A poly-hydroxylic molecule with approximate formula Cn(H2O)n.

D-glucose, a monosaccharide.   
α-D-glucopyranose, a monosaccharide.

Lactose, a disaccharide.   
Amylose, a polysaccharide.

Carbohydrate is a contraction of carbon hydrate, because the general carbohydrate molecular formula contains approximately one molecule of water for each carbon atom: Cn(H2O)n. This idea is supported by the reaction of sucrose (a disaccharide) with concentrated sulfuric acid (a dehydrating agent) to produce carbon and steam. Click on the image to play the video.