| Abbreviation | Definition |
|---|---|
| OFCC | Optical Fiber Communications Conference |
| OFCIOC | Optical Fiber Communication Conference, and International Conference on Integrated Optics and Optical Fiber Communication |
| OFE | Open Forum Europe |
| OFFICE | IEEE Computer Society OFFICE Automation Symposium |
| OFRC | Ohio Fair Racing Conference |
| OFS | Optical Fiber Sensors Topical Meeting |
| OGC | Optoelectronics Global Conference |
| OGDC | Open Game Development Conference |
| OGS | Organic Grower Summit |
| OHC | Ohio Heritage Conference |
| OHS | Open Hardware Summit |
| OIB | Objects in Bioinformatics |
| OIC | of the Islamic Conference |
| OIC | Options Industry Conference |
| OIC | Organisation of Islamic Conference |
| OIC | Organisation of the Islamic Conference |
| OIC | Organization of Islamic Conference |
| OIF | Optical Internetworking Forum |
| OIFW | Orlando International Fashion Week |
| OIMC | Oklahoma Indian Mission Conference |