Cut time (alla breve sign)
The French term for the barred half-circle sign indicating alla breve (cut time).
In the notation
In French musical terminology, C barré refers to the barred C sign placed at the start of a staff to indicate alla breve, a 2/2 meter in which two half notes are counted per bar instead of four quarter notes.
Musical use
The sign originates in medieval mensural notation, where a full circle denoted perfect, triple mensuration and a half circle denoted imperfect, duple mensuration. The bar through the C doubled the tempo, or the value of the beats, in that notation, a principle that survives in today's alla breve sign.
Cut time should be distinguished from the plain C sign, which denotes the regular 4/4 meter: both signs share the same historical origin but differ in their counting unit and, in practice, usually in the felt basic tempo as well.