In music, a mordent is an ornament indicating that the note is to be played with a single rapid alternation with the note above or below. Like trills, they can be chromatically modified by a small flat, sharp or natural accidental. The term comes from the Latin mordere, meaning "to bite".

The mordent is thought of as a rapid single alternation between an indicated note, the note above (the upper mordent) or below (the lower mordent) and the indicated note again.

The precise meaning of mordent has changed over the years. In the Baroque period, a mordent was a lower mordent and an upper mordent was a pralltriller or schneller. In the 19th century, however, the name mordent was generally applied to what is now called the upper mordent, and the lower mordent became known as an inverted mordent.

In other languages the situation is different: for example in German Pralltriller and Mordent are still the upper and lower mordents respectively. Also note that this ornament in French, and sometimes in German, is spelled mordant.