Breve — Chambers's Encyclopaedia

Breve, a note in Music. The name was originally applied to the shortest of the three notes used in early music, but is now appropriated to the longest note met with, and it occurs but seldom, except in church music, modern music being divided into bars which usually fall short of it in length. It has the time-value of two semibreves, and was formerly written thus, $\text{II}$ , now $\text{||}$ or $\text{|||}$ . The expression alla breve at the beginning of a piece—also denoted by the vertical stroke through the sign of common time, $\text{C}$ —signifies that the time-value of the notes is reduced to one-half.