OPN

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, recording alias of musician Daniel Lopatin
 * Olivary pretectal nucleus, a nucleus in the pretectal area, or pretectum
 * In mathematics, odd perfect number
 * Ora pro Nobis, Latin phrase litt. meaning "pray for us", often abbreviated as OpN in prayer books and breviaries
 * FM Operator Type-N, a series of sound chips made by Yamaha:
 * YM2203 (OPN)
 * YM2608 (OPNA)
 * YM2610 (OPNB)
 * YM2612 (OPN2)
 * YMF288 (OPN3)