FIW
| Acronym | Definition |
|---|---|
| FIW | Forchungsinstitut für Wärmeschutz (German: Research Institute for Thermal Protection) |
| FIW | Friendship Is Witchcraft |
| FIW | Fighter Interceptor Wing |
| FIW | Feature Interaction Workshop |
| FIW | Freesite Insertion Wizard (software utility) |
| FIW | Federal Interagency Workgroup (various government agencies) |
| FIW | Friends in War (website) |
| FIW | Fuel, Inspect, Wash (maintenance) |
| FIW | Federation Interprovinciale Wallonne (animal breeders association; Belgium) |
| FIW | Future Individual Weapon |