OPN may stand for:
- Osteopontin, a glycoprotein secreted by osteoblasts
- Object Process Network, a simulation model meta-language
- Optics & Photonics News, a magazine
- Oneohtrix Point Never, a musician
- Olivary pretectal nucleus, a nuclei in the pretectal area, or pretectum
- In mathematics, odd perfect number
- Yamaha YM2203, a sound chip
Usage examples of "opn".
All drs wide opn allow each off see another, all spls will carry revr.