In pharmacology, what does the abbreviation "PO" stand for?

The abbreviation "PO" stands for "per os," which is a Latin phrase meaning "by mouth." This term is commonly used in pharmacology and medical contexts to indicate that a medication is to be taken orally, as opposed to other routes of administration like intravenous or intramuscular. The oral route is one of the most common methods for delivering medications, as it is generally convenient for patients and allows for easy self-administration. Understanding this term helps healthcare professionals communicate clearly about medication administration, ensuring that patients receive their treatments correctly and safely.

The other options represent different medical terminologies but do not align with the specific meaning of "PO" in the context of medication administration. For example, "parenteral operations" does not relate to oral medication, "percutaneous" refers to entering through the skin, and "post operatively" refers to the period after surgery, none of which indicate oral administration.