Which root word refers to a vessel in medical terms?

The root word that refers to a vessel in medical terms is "Vas/o." This term comes from the Latin word "vas," which means vessel. In medical terminology, "vas/o" is commonly used to describe structures related to blood vessels, such as in the terms "vasodilation" (widening of blood vessels) and "vasoconstriction" (narrowing of blood vessels). This root captures the essence of the biological function regarding how fluids, especially blood, are transported throughout the body via various types of vessels.

In contrast, although "Angi/o" relates to blood vessels as well, it specifically denotes blood vessels or lymphatic vessels and is typically used in contexts involving imaging or conditions related to those vessels. "Vessel/o" is not a recognized root term in medical terminology, while "Ven/o" specifically refers to veins, which are a subtype of blood vessels, focusing only on those that carry blood towards the heart rather than encompassing all types of vessels. Therefore, "Vas/o" is the most accurate choice as it broadly represents the concept of a vessel in a more general sense.