- David Hiley
A sign placed, in modern notational practice, before a note, which alters its previously understood pitch by one or two semitones. The sharp (♯; Fr. dièse; Ger. Kreuz; It. diesis) raises a note by one semitone; the double sharp (𝄪; Fr. double dièse; Ger. Doppelkreuz; It. doppio diesis) raises it by two semitones. The flat (♭; Fr. bémol; Ger. Be; It. bemolle) lowers a note by one semitone; the double flat (♭♭; Fr. double bémol; Ger. Doppel-Be; It. doppio bemolle) lowers it by two semitones. The natural (♮; Fr. bécarre; Ger. Auflösungszeichen or Quadrat; It. bequadro) cancels a previous sharp or flat. A double sharp is changed to a single sharp by writing ♮♯ or occasionally ♯, a double flat to a single flat by ♮♭ or occasionally ♭.
For a discussion of the addition of accidentals to early music see Musica ficta; see also...