OMD
- 3-O-Methyldopa
- Clerics Regular of the Mother of God of Lucca
- Discalced Mercedarians
- OMD Worldwide
- Occult macular dystrophy
- Ohio-Meadville District
- Olympus OM-D series
- One Million Degrees
- One More Day (comics)
- Orchestral Manoeuvres in the Dark
- Orcs Must Die!
- Organic mental disorders
- Ormond railway station
- Orofacial myological disorders
- Oromandibular dystonia
- Osteomodulin