Which prefix means 'large' in medical terminology?

The prefix that means 'large' in medical terminology is 'mega-.' This term is derived from the Greek word 'megas,' which translates to 'great' or 'large.' In medical contexts, 'mega-' is often used to describe conditions or entities that are larger than normal, such as in the term 'megaly,' which refers to the enlargement of an organ (e.g., hepatomegaly means enlargement of the liver).

In contrast, 'micro-' signifies small or minute, often indicating conditions or structures that are diminutive. 'Meso-' refers to something intermediate, or middle, and does not imply size in either a large or small sense. 'Pseudo-' denotes falsehood or deception, indicating something that is not what it appears to be, rather than size relationships. Thus, 'mega-' is the accurate prefix for indicating large in medical terminology.