carbohydrate (n.) Look up carbohydrate at Dictionary.com
1851, from carbo-, comb. form of carbon, + hydrate (n.), denoting compound produced when certain substances combine with water, from Greek hydor "water" (from suffixed form of PIE root *wed- (1) "water; wet").
The name carbohydrate was given to these compounds because, in composition, they are apparently hydrates of carbon. In structure, however, they are far more complex. [Flood]