| Abbreviation | Definition |
|---|---|
| NALC | National Association of Letter Carriers |
| NAMB | National Association of Mortgage Brokers |
| NANU | Namibia African National Union |
| NARM | National Association of Reunion Managers |
| NASAWU | National Services and Allied Workers Union |
| NASU | Native American Student Union |
| NASU | Non Academic Staff Union |
| NASUP | Non Academic Staff Union of Polytechnics |
| NASUU | Non Academic Staff Union of Universities |
| NASUWT | National Association of Schoolmasters Union of Women Teachers |
| NATCA | National Air Traffic Controllers Association |
| NATU | National Association of Trade Unions |
| NAUL | National Amalgamated Union of Labour |
| NBCU | New Bedford Credit Union |
| NBCU | Northern Beaches Credit Union |
| NBPA | National Basketball Players Association |
| NBPA | National Black Police Association |
| NBU | New Brunswick Union |
| NCAA | National College Athletic Association |
| NCBU | National Confederation of Bank Union |