| Acronym | Definition |
|---|
| NIU➣Northern Illinois University |
| NIU➣Niue (ISO Country code) |
| NIU➣Northland International University (Wisconsin) |
| NIU➣Network Interface Unit |
| NIU➣Not in Use |
| NIU➣Naval Intelligence Unit (US Navy) |
| NIU➣National Interdiction Unit (Afghanistan) |
| NIU➣National I-Lan University (Taiwan) |
| NIU➣Nitrogen Inerting System |
| NIU➣Nagoya Imperial University (now Nagoya University; Japan) |
| NIU➣NATO Interface Unit |
| NIU➣Nacelle Interface Unit |
| NIU➣Northern International University (Magadan, Russia) |