| OAP | Office of Adolescent Pregnancy; old age pension, old age pensioner; ophthalmic artery pressure; oste... |
|---|---|
| OC | obstetrical conjugate; occlusocervical; office call; on call; only child; optic chiasma; oral contra... |
| O2cap | oxygen capacity |
| OCD | obsessive compulsive disorder; Office of Child Development; Office of Civil Defense; osteochondritis... |
| O2D | oxygen delivery |