| National Anthropological Archives | Academic & Science |
| N Acetylaspartic acid | Academic & Science |
| Nucleic Acid Amplification | Academic & Science |
| National Academy of Arbitrators | Academic & Science |
| National Alumni Association | Academic & Science |
| Northwestern Alumni Association | Academic & Science |
| National Association of Accountants (now Ima) | Accounts and Finance |
| Narrabri | Airport Code |
| National Association of Accountants | Business |
| National Apartment Association | Business |
| National Aquaculture Association | Business |
| Naphtalic Acetic Acid | Chemistry |
| National AfterSchool Association | Community |
| National Association of Appraisers | Community |
| Newburyport Art Association | Community |
| National Aeronautics Association | Community |
| National Aphasia Association | Community |
| Newspaper Association of America | Community |
| National Aerosol Association | Community |
| National Aeronautic Association | Community |
| National Auctioneers Association | Community |
| National Algae Association | Community |
| Nebraska Arborists Association | Community |
| Next Available Agent | Computing |
| Number of Attributes Accesses | Computing |
| Number of All Associations | Computing |
| Network Audio Adapter | General |
| National Apartment | General |
| North American Arms | General |
| Not An Answer | General |
| National Aviation Authority | General |
| Nevada Alternate Assessment | General |
| Not Another Acronym | General |
| Network Attached Audio | General |
| Negative Alien Agenda | General |
| North American Aviation | General |
| N Acetyl Aspartate | General |
| Northwest Automotive Alliance | General |
| Nippon Denso Abs Actuator | General |
| National Automobile Association | General |
| Norwegian Automobile Association | General |
| Northern Automotive Alliance | General |
| National Auto Academy | General |
| Newera Automotive Academy | General |
| Nimrokko Animal Army | General |
| Never Abbreviate Again! | General |
| Nutrition Academic Award | General |
| National Aviation Academy | General |
| not an actuary | General |
| North America Administrators | General |
| Network Address Authority | Governmental |
| Not Army Aviation | Governmental |
| Neighborhood Assistance Act | Governmental |
| Newly Accessible Area | Governmental |
| National Airspace Analysis | Governmental |
| North American Alliance | Governmental |
| No Acronym Assigned | Governmental |
| Network Addressing Authority | Governmental |
| National Agents Alliance | Governmental |
| New America Alliance | Governmental |
| Name Address Authority | Governmental |
| No Apology Accepted | Internet |
| Nothing At All | Maths |
| No apparent abnormalities | Medical |
| National Autism Association | Medical |
| Neutron Activation Analysis | Physics Related |
| Narrabri, New South Wales, Australia | Regional |
| National Archery Association | Sports |
| Newton Athletic Association | Sports |
