The Combining Vowel

The letter o connects word parts and follows a few predictable rules.

The letter o is often a connector. It makes word parts easier to say. It usually carries no medical meaning.

Keep it between two roots: gastr/o/enter/itis.

Usually drop it before a suffix beginning with a vowel: hepat/itis, not hepatoitis.

Keep it before a suffix beginning with a consonant: cardi/o/logy.

Real medical language contains rebels. Your job is recognition, not policing every spelling rule.