1. A musical interval equal to one twelfth of an octave, or a sharp symbol (♯) used in musical notation.
Usage: music; technical
2. In typography and printing, a small mark or sign used to indicate a division or distinction.
Usage: archaic; rare

Examples

• The composer used a diesis to raise the pitch of the note by a semitone.
• In equal temperament tuning, a diesis represents a specific microtonal interval.
• The diesis symbol appears frequently in classical sheet music.
• Musicians must understand the diesis to read accidentals correctly.