| Abbreviation | Definition |
|---|---|
| NR | not refillable |
| NS | normal saline (0.9%) |
| NSAIA(s) | non-steroidal anti-Inflammatory agent(s) |
| NSAID(s) | nonsteroidal anti-inflammatory drug(s) |
| o | pint |
| O.M.D./D.O.M | Oriental Medical Doctor / Doctor or Oriental Medicine |
| o.p.d. | once per day |
| o.s. | oculus sinister - left eye |
| o.u. | oculus uterque - both eyes |
| o2 | both eyes, sometimes written as o2 |
| OCP | Oral Contraceptive Pills |
| OD | Once a Day |
| OD | Once Daily |
| ODB | Ontario Drug Benefit |
| ODCP | Office of Drug Control Policy |
| OEPP | Opioid Essential Prescription Package |
| OFC | Ofloxacin |
| OM | Omne Mane (every morning) |
| on | omne nocte - every night |
| OPI | Opioid Prescription Intervention |