fm
- n modulation of the frequency of the (radio) carrier wave
- n a radioactive transuranic metallic element produced by bombarding plutonium with neutrons
fmri
- n a form of magnetic resonance imaging of the brain that registers blood flow to functioning areas of the brain
fo
- n an officer holding the rank of major or lieutenant colonel or colonel
fo'c'sle
- n living quarters consisting of a superstructure in the bow of a merchant ship where the crew is housed