| NOT | nocturnal oxygen therapy |
|---|---|
| NOTT | nocturnal oxygen therapy trial |
| O2a | oxygen availability |
| 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... |