OMM
- Digital object memory
- Of Mice and Men
- Of Monsters and Men
- Old Man Murray
- Om
- One Magnificent Morning
- One Million Moms
- Open music model
- OpenSource Maturity Model
- Order of Military Merit (Canada)
- Organization of Mozambican Women
- Original Mountain Marathon
- Osteopathic manipulative medicine
- Outer mitochondrial membrane
- THX 1138
- The Observer
- The One Million Masterpiece
- World Meteorological Organization