Which prefix indicates something that is "large" in size?

The prefix that indicates something that is "large" in size is "mega-." This term is commonly used in both medical and scientific contexts to denote something that is significantly larger than normal. For example, "megacolon" refers to an abnormally enlarged colon, while "megabyte" refers to a unit of digital information that is significantly larger than a kilobyte. This prefix effectively conveys the idea of largeness or increased magnitude.

In contrast, the other prefixes have different meanings: "endo-" refers to something within or inside; "hypo-" indicates a lower or below normal level; and "dys-" relates to difficulty or abnormality. Understanding these prefixes can greatly enhance comprehension of medical terminology and improve communication in the healthcare environment.