| US/LS | upper strength/lower strength [ratio] |
|---|---|
| OCP | octacalcium phosphate; ocular cicatricial pemphigoid; oral case presentation; oral contraceptive pil... |
| OET | oral endotracheal tube; oral esophageal tube |
| OHI | Occupational Health Institute; operative hypertension indicator; oral hygiene index; Oral Hygiene In... |
| ad | add [Lat. adde] let there be added [up to a specified amount] [Lat. addetur]; axiodistal; right ear ... |