usage: a degree on the Fahrenheit scale of temperature
2. fluorine, F, atomic number 9, chemical element, element, gas, halogen
usage: a nonmetallic univalent element belonging to the halogens; usually a yellow irritating toxic flammable gas; a powerful oxidizing agent; recovered from fluorite or cryolite or fluorapatite
3. farad, F, capacitance unit
usage: the capacitance of a capacitor that has an equal and opposite charge of 1 coulomb on each plate and a voltage difference of 1 volt between the plates
4. F, f, letter, letter of the alphabet, alphabetic character