| Abbreviations | Meaning |
 | OCN | Oculomotor Nucleus; Oncology Certified Nurse; Osteocalcin |
 | ODD | Oculodentodigital [dysplasia]; Oppositional Defiant Disorder; Osteodental Dysplasia |
 | OH | Osteopathic Hospital |
 | OI | Osteogenesis Imperfecta |
 | OIC | Organized Indigenous Caregiving; Osteogenesis Imperfecta Congenita |
 | OIF | Osteogenesis Imperfecta Foundation |
 | OIF | Observed Intrinsic Frequency; Oil Immersion Field; Open Internal Fixation; Osteogenesis Imperfecta Foundation |
 | OM | Osteomalacia |
 | OM | Osteomyelitis |
 | OM | Osteopathic Manipulation |
 | OM&S | Osteopathic Medicine And Surgery |
 | OMERACT | Outcome Measures In Rheumatoid Arthritis Clinical Trial |
 | OMG | Object Management Group; Oligodendrocyte-myelin Glycoprotein; Osteopathic Medical School Graduate |
 | OMS | Osteomyelosclerosis |
 | OMT | Object Modeling Technique; Ocular Microtremor; O-methyltransferase; Ophthalmic Medical Technician Or Technologist; Osteopathic Manipulative Therapy |
 | ON | Occipitonuchal; Office Nurse; Olfactory Nucleus; Onlay; Optic Nerve; Orthopedic Nurse; Osteonecrosis; Osteonectin; Overnight |
 | ONFH | Osteonecrosis Of The Femoral Head |
 | OO | Osteoid Osteoma |
 | OP | Osteoporosis |
 | OPG | Osteoprotegerin |
 | OPI | Osteoblastic Proliferation Index |
 | OPN | Ophthalmic Nurse; Osteopontin |
 | OPS | Operations; Optical Position Sensor; Osteoporosis-pseudolipoma Syndrome; Outpatient Service; Outpatient Surgery |
 | OPS | Operations; Optical Position Sensor; Optimal Parameter Search [algorithm]; Osteoporosis-pseudolipoma Syndrome; Outpatient Service; Outpatient Surgery |
 | ORBD-NRC | Osteoporosis And Related Bone Diseases - National Resource Center |
 | ORSA | Osteoclast Resorption Stimulating Activity |
 | ORSA | Osteoclast Resorption Stimulating Activity; Oxacillin-resistant Staphylococcus Aureus |
 | OS | Bone |
 | OS | Osteogenic Sarcoma (context Bone Tumors) |
 | OS | Osteogenic Sarcoma |
 | OS | Osteosarcoma |
 | OS | Osteosclerosis |
 | OS-CS | Osteopathia Striata-cranial Sclerosis [syndrome] |
 | OSF | Organ System Failure; Osteoclast-stimulating Factor; Outer Spiral Fiber; Overgrowth Stimulating Factor |
 | OSF | Open Software Foundation; Organ System Failure; Osteoclast-stimulating Factor; Outer Spiral Fiber; Overgrowth Stimulating Factor |
 | OSRC | Osteosarcoma |
 | OSTEO | Osteoarthritis; Osteomyelitis; Osteopathy |
 | OSTOP | Osteoporosis Society Of British Columbia |
 | OV | Oculovestibular; Office Visit; Oncovirus; Osteoid Volume; Outflow Volume; Ovalbumin; Ovary; Overventilation; Ovulation |
 | PACE | People With Arthritis Can Exercise [program] |
 | PAO | Periacetabular Osteotomy |
 | PBM | Peak Bone Mass; Peripheral Basement Membrane; Peripheral Blood Mononuclear [cell]; Placental Basement Membrane |
 | PBS | Planar Bone Scan |
 | PCLI | Bone Marrow Plasma Cell Labeling Index |
 | PDB | Paget Disease Of Bone |
 | PGAP | Pilot Geriatric Arthritis Program |
 | PLO | Polycystic Lipomembranous Osteodysplasia |
 | PLO-SL | Polycystic Lipomembranous Osteodysplasia With Sclerosing Leukoencephalopathy (Nasu-Hakola Syndrome) |
 | PMO | Postmenopausal Osteoporosis; Principal Medical Officer |
 | POA | Pancreatic Oncofetal Antigen; Phalangeal Osteoarthritis; Preoptic Area; Primary Optic Atrophy |