dièse

Dièse is the French term for the sharp in Western musical notation, as well as the symbol used to indicate a raised pitch. When a dièse appears before a note on the staff, the note is sharpened by one semitone compared with its natural form. For example, C dièse (C#) is one semitone higher than C natural. Dièses can appear in key signatures to indicate that certain notes are regularly sharpened throughout a piece, and they can be added or canceled by accidentals such as the natural sign (bécarre) or other sharps.

In standard notation, there is also a concept of the double dièse, or double sharp, which raises a pitch by two semitones. This is typically notated with a distinct symbol (often resembling a stylized “x”), and is used in various keys and contexts, including some pieces of musical theory and early music practice.

Beyond music, the word dièse is also used in French to name the symbol # itself. In digital and social media contexts, this symbol is commonly referred to as a hashtag, and the broader term mot-dièse is used for hashtags in French.

Etymology and relation to other terms: the term derives from French usage in musical notation to denote sharp pitch alterations. It is distinct from bémol, the French term for flat, which lowers a pitch by a semitone. In notation and theory, dièse and natural signs interact to shape the chromatic and diatonic relationships within scales and harmonies.