What does the prefix "endo-" indicate in medical terms?

The prefix "endo-" in medical terminology signifies "inside" or "within." This prefix is derived from the Greek term "endon," which means "inside" or "within." It is commonly used in various medical terms to indicate structures or processes that occur internally. For example, "endocardium" refers to the inner lining of the heart, emphasizing that it is located within the heart's chambers.

Understanding this prefix is crucial for accurately interpreting medical terminology, as it helps to provide context about the location or function of anatomical structures. Other options, although they denote distinct meanings, do not align with the specific notion of "inside" that "endo-" conveys.