| O&P | Operating and Planning 
| Others |
| O&P | Operations and Procedures
| Others |
| O&P | Ova and Parasite
| Others |
| O&P | Ova and Parasites
| Others |
| O.P. | Osmotic Pressure
| Others |
| OP | O2 Page
| Others |
| OP | Obnoxious Preppie
| Others |
| OP | Obras Publicas
| Others |
| OP | Observation Point
| Others |
| OP | Observation Post
| Others |
| OP | Occasional Paper
| Others |
| OP | occipitoparietal
| Others |
| OP | Occiput Posterior
| Others |
| OP | Occlusal Plane
| Others |
| OP | Occupancy Permit
| Others |
| OP | Ocean Pacific
| Others |
| OP | Oceanic Plagiogranites
| Others |
| OP | Octave Plateau
| Others |
| OP | Octo Pest
| Others |
| OP | oesophagopharyngeal
| Others |
| OP | Off Premises
| Others |
| OP | Off Pump
| Others |
| OP | Off Topic
| Others |
| OP | Off-base Privileges
| Others |
| OP | Office of Preference
| Others |
| OP | Office of Protector
| Others |
| OP | Office Products
| Others |
| OP | Official Photographer
| Others |
| OP | Official Publication
| Others |
| OP | Oil Pan
| Others |
| OP | Old Prison
| Others |
| OP | Olfactory Pit
| Others |
| OP | On Plan
| Others |
| OP | On point
| Others |
| OP | On Program
| Others |
| OP | Oncotic Pressure
| Others |
| OP | One Piece
| Others |
| OP | One Power
| Others |
| OP | Ontario Public
| Others |
| OP | Opaque
| Others |
| OP | Open Palm
| Others |
| OP | Open Platform
| Others |
| OP | Open Plug
| Others |
| OP | Open Pollinated
| Others |
| OP | Open Position
| Others |
| OP | Opening Post
| Others |
| OP | Opening Pressure
| Others |
| OP | Operating Plan
| Others |
| OP | Operating Player
| Others |
| OP | OPeration
| Others |
| OP | Operational Publication
| Others |
| OP | Operationssaal
| Others |
| OP | Operative Paragraph
| Others |
| OP | Operative Procedure
| Others |
| OP | Operator Panel
| Others |
| OP | Operator Produksi
| Others |
| OP | opium
| Others |
| OP | Opponens Pollicis
| Others |
| OP | Opportunity Profile
| Others |
| OP | OPposite
| Others |
| OP | Optimistic Protocols
| Others |
| OP | Optimum Price
| Others |
| OP | Optional Procedure Mailing System
| Others |
| OP | OPtometry
| Others |
| OP | Oral Presentation
| Others |
| OP | Orange Pekoe
| Others |
| OP | Orange Potatoes
| Others |
| OP | Order of Preachers
| Others |
| OP | Ordnance Publication
| Others |
| OP | Organic Percussion
| Others |
| OP | Organising Pneumonia
| Others |
| OP | Organo-Phosphate
| Others |
| OP | Original Post
| Others |
| OP | Original Poster
| Others |
| OP | OroPharyngeal
| Others |
| OP | OroPharynx
| Others |
| OP | Orthographic Projection
| Others |
| OP | osteopaenia
| Others |
| OP | osteopontin
| Others |
| OP | OsteoPorosis
| Others |
| OP | Other People's
| Others |
| OP | Out of print
| Others |
| OP | Out-Patient
| Others |
| OP | Outline Processor
| Others |
| OP | Outpatient
| Others |
| OP | Outside Partner
| Others |
| OP | Outstanding Performer
| Others |
| OP | Over Powered
| Others |
| OP | Over Powerfull
| Others |
| OP | Over-Powered
| Others |
| OP | Overall Position
| Others |
| OP | Overland Park, Kansas
| Others |
| OP | OverPowered
| Others |
| OP | OverProof
| Others |
| OP | Overton Park, Memphis, Tennessee
| Others |
| OP | Owner Pays
| Others |
| OP | Oxidative Phosphorylation
| Others |
| OP | Oxycontin Purdue
| Others |
| OP | Oxygen Purge
| Others |
| Op. | Opus number
| Others |