| Abbreviation | Definition |
|---|---|
| NMS | New Medical Ship |
| NSC | Nigerians Shippers Council |
| NSSN | New Nuclear-powered Attack Submarine |
| NSTM | Naval Ships Technical Manual |
| o/b | overboard |
| O/T | Oil Tanker |
| OBB | Old Battleship |
| OC | Outrigger Canoe |
| OIV | Offshore Installation Vessel |
| OM | Open Motorboat |
| OPSV | Offshore Platform Support Vessel |
| PACV | Patrol, Air Cushion Vehicle |
| PB | Patrol Boat |
| PBR | River Patrol Boat (Patrol Boat, River) |
| PC | Patrol Craft |
| PCC | Pure Car Carrier |
| PCE | Patrol Craft, Escort |
| PCER | Patrol Craft Escort, Rescue |
| PCF | Patrol Craft Fast |
| PCG | Patrol Craft, Guided Missile |