carbohydrate

Etymology

From their general formula Cₙ(H₂O)ₙ; they were once thought to be hydrates of carbon.

noun

1. (organic chemistry, nutrition) A sugar, starch, or cellulose that is a food source of energy for an animal or plant.
   These microbes are primarily responsible for breaking down cellulose and other carbohydrates into volatile fatty acids (VFAs).
   Oxygen levels on Earth skyrocketed 2.4 billion years ago, when cyanobacteria evolved photosynthesis: the ability to convert water and carbon dioxide into carbohydrates and waste oxygen using solar energy. 2013 September-October, Katie L. Burke, “In the News”, in American Scientist
2. (colloquial, by extension, metonymically) Any food rich in starch or other carbohydrates.
   I'm cutting down on carbohydrates like bread and pasta.