| OHI | Occupational Health Institute; operative hypertension indicator; oral hygiene index; Oral Hygiene In... |
|---|---|
| ORS | olfactory reference syndrome; oral rehydration solution; oral surgery, oral surgeon; Orthopaedic Res... |
| OHI-S | Oral Hygiene Instruction-Simplified |
| OCP | octacalcium phosphate; ocular cicatricial pemphigoid; oral case presentation; oral contraceptive pil... |
| OET | oral endotracheal tube; oral esophageal tube |