O
- OBE – Overcome by Events (DoD)
- OCONUS – Outside Continental United States
- OM – On the Move (Normally just spelled out Oscar Mike)
- O&M, MC – Operations & Maintenance, Marine Corps (U.S. Navy)
- O&M, N – Operations & Maintenance, Navy (U.S. Navy)
- OODA – Observe, Orient, Decide, And Act
- OP – Observation Post
- ORM – Operational Risk Management
- OSM – Oh Shit Moment (U.S. Marine Corps)
- OSP – On Site Procurement
- OPORD – Operations Order
- OPSEC – Operations Security
- OTF – Out There Flapping (Airborne)
- OTV – Outer Tactical Vest
Read more about this topic: List Of U.S. Government And Military Acronyms