OP sive O.P.
- (mil.) observation post
- Ordo Praedicatorum sive Ōrdō Praedicātōrum; Order of Preachers (the Dominicans)
OP sive O.P. sive o.p.
- out of print
- opening sive opening theme
- (shortwave transmission) operate; operator
- (Internet) original poster; original post
- (British Theater) opposite prompt
- (opening) intro