| OI | obturator internus; occasional insomnia; opportunistic infection; opsonic index; orgasmic impairment; orientation inventory; orthoiodohippurate; osteogenesis imperfecta; oubain insensitivity; oxygen intake |
|---|---|
| OIC | osteogenesis imperfecta congenita |
| OID | optimal immunomodulating dose; Organism Identification Number; oxygen insufflation device |
| OIF | observed intrinsic frequency; oil immersion field; Osteogenesis Imperfecta Foundation |
| OIG | Office of the Inspector General |
| OIH | Office of International Health; orthoiodohippurate; ovulation-inducing hormone |
| OILD | occupational immunologic lung disease |
| oint | ointment |
| OIP | organizing interstitial pneumonia |
| OIR | Office of Information Resources; Office of International Research |