The term 'CLEF' is a four-letter word that is used in music notation. It is a symbol that is placed at the beginning of a staff to indicate the pitch of the notes written on the staff. The CLEF is usually either a C, F, or G CLEF, with the C CLEF being the most common. The C CLEF indicates that middle C is the pitch of the notes written on the staff, while the F CLEF indicates that F below middle C is the pitch of the notes written on the staff, and the G CLEF indicates that G above middle C is the pitch of the notes written on the staff.