Time signature \Time signature\ (Music)
A sign at the beginning of a composition or movement, placed
after the key signature, to indicate its time or meter. Also
called {rhythmical signature}. It is in the form of a
fraction, of which the denominator indicates the kind of note
taken as time unit for the beat, and the numerator, the
number of these to the measure.
[Webster 1913 Suppl.]