Double whole note

In music, a double whole note (American), breve (international), or double note (Baker 1895, 133) is a note lasting two times as long as a whole note (or semibreve). In medieval mensural notation, the brevis (ancestor of the modern breve) was one of the shortest note lengths—hence its name, which is the Latin etymon of "brief" (Read 1969, 14). In "perfect" rhythmic mode, the brevis was a third of a longa, or in "imperfect" mode half a longa (for full details of the complications here, see for example Hoppin 1978). However, in modern music notation it is the longest note value still in common use (Gehrkens 1914, 106).