Which of the following is a root in a medical term? megaly cardio osis semi

The root in a medical term from the options provided is "cardio".

Here's why:

1. In medical terminology, a root is the base of a word that gives it its fundamental meaning.

2. "Megaly", "osis", and "semi" are not roots but suffixes or prefixes. "Megaly" is a suffix meaning enlargement, "osis" is a suffix meaning condition, and "semi" is a prefix meaning half.

3. "Cardio" is a root word in medical terminology, and it refers to the heart. For example, in the term "cardiology", "cardio" is the root that gives the term its basic meaning related to the heart, and "-logy" is a suffix meaning the study of.

So, "cardio" is the root in a medical term among the options given.