Which prefix carries the meaning of "excessive" in medical terminology?

The prefix that conveys the meaning of "excessive" in medical terminology is "poly-." This prefix is commonly used to indicate an abundance or an excessive quantity of something. For example, in terms like "polydipsia," which refers to excessive thirst, or "polyuria," which implies excessive urination, the prefix clearly denotes an abnormal increase.

In contrast, "multi-" typically means "many" or "multiple," but not necessarily excessive. "Semi-" conveys the meaning of "half," indicating a partial presence rather than an increase. "Hemi-" is similar, referring specifically to half of something, such as in "hemiplegia," which means paralysis on one side of the body. Thus, "poly-" is the most appropriate prefix for signifying an excess.