The definition of a chord in music is this: three or more single pitches heard simultaneously. Depending on the harmonic style, chords may be consonant, implying repose, or dissonant, implying subsequent resolution to and by another chord. In traditional Western harmony, chords are formed by superimpositions of intervals of a third. There are several different chord types, and each chord type has a particular sound. Chords are built off of one note, called the root note.