Which prefix refers to a position that is outside?

The prefix that refers to a position outside is "Exo-." This prefix comes from the Greek word "exō," which means "outside" or "outer." It is commonly used in medical terminology to describe structures or conditions that are situated externally in relation to a reference point, such as in "exoskeleton," which refers to an external skeleton found in some animals.

In contrast, the prefix "Mid-" typically refers to a middle position, suggesting centrality rather than an external location. "Inter-" indicates a position between two points or structures, implying a connection rather than an external position. Lastly, "Endo-" signifies a position that is inside or within, such as in "endoscopy," which refers to examination of the inside of a body cavity or organ. Together, these distinctions clarify why "Exo-" is the most appropriate choice for indicating an outside position.