Note of the scale, 4th degree of natural scale of C. Thus F♭, F♭♭, F♮, F♯, F♯♯. Keys of F major and F minor, F♯ ma jor, F♯ minor. ‘In F’ is also an indication of transposing instr. on which written note C sounds as F (e.g. hn., F tpt.). The F clef is the bass clef.