| OAP | Office of Adolescent Pregnancy; old age pension, old age pensioner; ophthalmic artery pressure; oste... |
|---|---|
| OAPP | Office of Adolescent Pregnancy Programs |
| PN | papillary necrosis; parenteral nutrition; penicillin; perceived noise; percussion note; periarteriti... |
| P&N | psychiatry and neurology |
| Psy | psychiatry; psychology |