Final answer:
NPO stands for 'Nothing by mouth,' a medical directive for patients not to consume food or drink orally before certain medical procedures or tests.
Step-by-step explanation:
The abbreviation NPO stands for 'Nothing by mouth.' This is a medical instruction indicating that a patient should not consume any food or liquids orally. It's commonly used before certain medical procedures or tests, such as surgeries that require general anesthesia or if the patient has certain medical conditions that affect the ability to swallow or digest food safely.