Breve

From the Latin word, brevis, meaning short, this was formerly the shortest time value in all of musical notation. However, now that the longer note values have fallen into disuse, it is now the longest (that is, twice the length of the semi-breve). The musical expression alla breve is typically interpreted to mean “double the speed,” so that, as an example, a 4/4 time signature is played as 2/2. This term is rarely used today, with the exception of certain chamber music written for period instruments.