Which prefix means "within" in medical terminology?

The prefix "intra-" means "within" in medical terminology. This prefix is used to indicate something that occurs inside a specific structure or area of the body. For instance, "intravenous" refers to something being administered within a vein, while "intraoperative" pertains to the time during a surgical operation. This specificity of denoting a location or action taking place inside something highlights its meaning as "within."

The other prefixes do not convey the same meaning. "Macro-" refers to something large or extensive, generally describing size rather than location. "Myo-" is related to muscle tissue, often indicating a relationship to muscle (as in "myocardium," which refers to heart muscle). "Neo-" signifies newness or recent development, often used in contexts like "neoplasm," which is a new or abnormal growth of tissue. Thus, "intra-" is the appropriate prefix for indicating a location "within" something.