FO

Fo may refer to:

• Face Off
• Abbreviation for the computer game Fallout (computer game)
• Faroe Islands (country code FO)
• Faroese language (language code fo)
• Field officer, a senior army officer
• First-order logic, a system of mathematical logic
• First Officer, or co-pilot on an airliner
• Flying Officer, a Royal Air Force rank
• Dario Fo, Italian playwright and Nobel laureate
• Football Outsiders, a website devoted to statistical analysis of the NFL
• Force Ouvrière, a French trade unions confederation
• Foreign and Commonwealth Office of the British government
• Foreign object
• Foreign Objects, a Pennsylvania music group
• Forum, an online communications medium
• Forward Observer, a soldier who directs artillery fire
• Fourier number (Fo) in physics
• Frame optional military symbol
• Abbreviation for Fuck Off
• Fuel oil
• Furka-Oberalp-Bahn, a Swiss railway
• Number 4 (slang abbreviation fo’)
• XSL Formatting Objects (XSL-FO)
• Airlines of Tasmania IATA airline designator
• Fo, one of the 9 departments of the Houet Province of Burkina Faso.
• FO, a subunit of F1FO type ATPase