| Abbreviation | Definition |
|---|---|
| OFDS | Oral facial digital syndromes |
| OFDS | Oro Facial Digital Syndrome |
| OFDS | Oro facial digital syndromes |
| OGS | Older Guy Syndrome |
| OHS | obesity hyperlipidemia syndrome |
| OHSS | Ovarian Hyper Stimulation Syndrome |
| OIIS | Oxaliplatin Immune Induced Syndrome |
| OOS | overseas occupational syndrome |
| OPWSA | Ontario Prader-Willi Syndrome Association |
| OQDS | Olive Quick Decline Syndrome |
| OSX | Opitz Syndrome X |
| PAIS | Partial Androgen Insensitivity Syndrome |
| PAND | Primary Adrenocortical Nodular Dysplasia |
| PANS | Positive And Negative Syndrome |
| PANSS | Positive and Negative Syndrome Scale |
| PAPS | Prostaglanding Associated Periorbitopathy Syndrome |
| PASC | Post-Acute Sequelae of COVID-19 |
| PAWS | Post Acute Withdrawal Syndrome |
| PBTS | Pistachio Bushy Top Syndrome |
| PCOS | Polycystic ovary syndrome |