FID can mean:
- International Federation for Information and Documentation
- Financial Institutions Duty, an Australian tax
- Flame ionization detector, an instrument for analysing gas composition
- Free induction decay of excited atomic nuclei
- .fid, an extension for a file acquired on vnmr nuclear magnetic resonance software
- Fuck...I'm Dead, a deathgrind band
- Free indirect discourse or free indirect speech
- Foreign internal defense
- F.I.D., a double CD album set by Japanese noise musician Masami Akita