It comes from the Greek word "glykys" which means sweet.
You can see this root in many words related to sugars and carbohydrates:
* Glycogen: A complex carbohydrate stored in the liver and muscles.
* Glycolysis: The breakdown of glucose to produce energy.
* Glycoprotein: A protein with a sugar attached to it.
* Glycolipid: A lipid with a sugar attached to it.