• f6 (cigarette), a brand of cigarette produced in Dresden, Germany
• F 6 Karlsborg, a former Swedish Air Force wing
• F-6 Skyray (F4D Skyray), a 1950s/1960s US Navy jet fighter
• Form F-6, a U.S. Securities and Exchange Commission filling
• FPV F6, an Australian-made series of turbocharged 6-cylinder cars by Ford Performance Vehicles
• GS&WR Class F6, a Great Southern and Western Railway Ireland Steam Locomotives
• Hannover F.6, a 1918 German ground attack aircraft
• Hunter F 6, a F 4 with Sapphire 101 engine Hawker Hunter fighter aircraft variant
• Milwaukee Road class F6, a 1925 American 4-6-4 steam locomotive model
• Nikon F6, a professional-level SLR 35mm camera
• Shenyang F-6, an export version of the Chinese Shenyang J-6 jet fighter
• The Ascent of F6, tragedy by W. H. Auden and Christopher Isherwood

and also :

• FaroeJet IATA code
• F-6, a photo-reconnaissance variant of the P-51 fighter
• F6 Freeway in Wollongong, NSW, Australia
• F sixth octave musical note, a fourth above Soprano C
• F6F Hellcat, an American WWII fighter aircraft, most successful naval aircraft in history
• a function key on a computer keyboard
• F06 : Other mental disorders due to brain damage and dysfunction and to physical disease ICD-10 code