| Acronym | Definition |
|---|
| ONA | Ontario (Amtrak station code; Ontario, CA) |
| ONA | Online News Association (Washington, DC) |
| ONA | Overseas News Agency (UK) |
| ONA | Open Network Architecture |
| ONA | One Number Access |
| ONA | Online Network Access |
| ONA | Open-Network Architecture |
| ONA | Ontario Nurses Association |
| ONA | Open and Affirming |
| ONA | Office of National Assessments (Australia) |
| ONA | Ohio Nurses Association |
| ONA | Oregon Nurses Association |
| ONA | Overseas National Airways (1950-1978) |
| ONA | Other Needs Assistance (US FEMA program) |
| ONA | Oklahoma Nurses Association |
| ONA | Open Network Access (mobile communications) |
| ONA | Operational Net Assessment |
| ONA | Office of Net Assessment |
| ONA | Order of the Nine Angles (Satanism) |
| ONA | Outreach to New Americans (National Crime Prevention Council, Bureau of Justice Assistance and the Office of Refugee Resettlement) |
| ONA | Organizational Needs Assessment (Canada) |
| ONA | Optimum Natural Arrangements (landscape contract business; Sequim, WA) |
| ONA | Original Net Anime |
| ONA | On-Line Archive |
| ONA | Ocicats of North America (various locations) |
| ONA | Orienteering North America (magazine) |
| ONA | Outreach North America (Associate Reformed Presbyterian Church) |
| ONA | Of New Astronomy (apparel company) |
| ONA | Optical Network Architecture |
| ONA | OSI Network Address |
| ONA | Omnium North Africa |
| ONA | Optimal Nutritional Allowance |
| ONA | Office of Negotiations and Agreements (Foreign Agricultural Service, United States Department of Agriculture) |
| ONA | Onsite Network Administrator |
| ONA | Onondaga Numismatic Association |
| ONA | Office of Network Administration |