What is the medical abbreviation for mouth?

The abbreviation "Os" is derived from the Latin word for mouth, "os," which means mouth or opening. In medical terminology, it is widely utilized, particularly in pharmacology and anatomy, to refer specifically to the oral cavity. Understanding this abbreviation is crucial for healthcare professionals, as it often appears in medical records and prescriptions to indicate routes of administration for medications or to describe certain medical conditions.

In contrast, the other options represent different terms: "R.O." stands for rectal or may refer to route of administration for enema, "M.O." is not a standard medical abbreviation related to mouth but could confuse with others used in different contexts, and "P.O." stands for per os, which also means by mouth but is typically used to indicate the route of medication administration rather than as a standalone abbreviation for mouth. Thus, "Os" is the most accurate choice to signify mouth in a direct sense.