Which prefix means many or multiple?

The prefix "poly-" is derived from Greek and means "many" or "multiple." It is commonly used in medical terminology to indicate a condition involving a large number of something. For example, "polyuria" refers to excessive urination, indicating a condition characterized by the production of large volumes of urine.

The other prefixes provided have different meanings; "contra-" refers to opposition or against, typically used in terms like "contraindications," which highlight factors that would prevent the use of a certain treatment. "Macro-" signifies something large or abnormal in size, such as in "macrophage," which is a type of large white blood cell. Lastly, "melan/o-" pertains to black or dark pigment, often used in terms related to skin conditions or pigmentation, such as "melanoma." Each of these prefixes serves distinct purposes in medical terminology, making "poly-" the clear choice for denoting multiplicity.