metre

In music, refers to the number and value of the beats in a bar of music. It is also known as time. Metre is different from rhythm in that it is regular (although the number can change as in the additive metres of African music and the works of Olivier Messiaen), whereas rhythm is irregular.

The metre or time of the music may be: duple, two beats to a bar; triple, three beats to a bar; quadruple, four beats to a bar; or indeed any other number such as eleven in Bulgarian folk music.

Time may also be simple or compound. In simple time each beat is a whole note (not dotted) that can be divided by two. For example, in 4/4 (simple quadruple time) there are four quarter-note beats to a bar and each beat can be divided into two eighth notes. In compound time each beat is a dotted note that can be divided by three. For example, in 6/8 (compound duple time) there are two dotted quarter-note beats to a bar, each beat can be divided into three eighth notes.

In music, the numerical sign for time is known as a time signature. This is always found at the beginning of the music and consists of two numbers shown as a fraction of a whole note. The upper number is the number of beats in a bar and the lower number the type of beat. For example, 2/2 means two half-note beats to the bar; 3/4 means three quarter-note beats to the bar; and 6/8 means two beats each of three eighth notes.