FIM
- Facing Identification Mark
- Field ion microscope
- File integrity monitoring
- Fim switch
- Finnish markka
- First-in-man study
- Fisher information matrix
- Flight interruption manifest
- Flint Institute of Music
- Flow-following, finite-volume Icosahedral Model
- Focused impedance measurement
- Forefront Identity Manager
- Fox Interactive Media
- Free immersion apnea
- Functional Independence Measure
- Fédération Internationale de Motocyclisme
- Independent Moralizing Front
- Institute for Mathematical Research
- International Federation of Musicians
- Italian Federation of Metal Mechanics