hemidemisemiquaver

Hemidemisemiquaver is the British English name for the sixty-fourth note in Western musical notation. It is equivalent to the American sixty-fourth note or 64th note. The term sits in a family of note values beginning with semiquaver (sixteenth) and progressing through demisemiquaver (thirty-second) to hemidemisemiquaver (sixty-fourth).

The 64th note is written with four flags or beams on its stem. It represents one sixty-fourth of a whole note. In 4/4 time, when the beat is a quarter note, a 64th note lasts one sixteenth of a beat, making it a very short subdivision used mainly in rapid passages or highly detailed rhythmic textures.

Use and context: Because of its brevity, the hemidemisemiquaver appears primarily in fast passages, virtuosic keyboard writing, or intricate orchestral textures. Composers employ it to convey rapid scales, arpeggios, or ornamental figures. In notation, 64th notes are often grouped in beams of four to show their subdivision within a beat or measure.

Name and regional usage: The word is long and characteristic of British usage; American terminology favors the shorter “sixty-fourth note.” Both refer to the same rhythmic value, and the distinction is primarily historical and regional.