What root word means bag?

The correct root word that means bag is "cyst." In medical terminology, "cyst" refers to a sac-like structure containing fluid, which aligns with the concept of a 'bag' that holds or encases something. Cysts can be found in various tissues and organs throughout the body and are often described as abnormal growths that can appear in or around other structures.

In contrast, "pouch" is a more common term and is not typically used in medical terminology to denote a specific root. "Foll" is derived from "follicle," which refers to a small sac or cavity, but it does not directly translate to 'bag.' "Vesic" comes from the word "vesicle," which is also a small sac, specifically one that contains a liquid, but it does not have the same connotation as "cyst" in terms of a rounded or bag-like encapsulation associated with cysts. Therefore, when focusing on the root word meaning 'bag,' "cyst" is the correct term to use.