polyphony (pəlĬf´ənē), music whose texture is formed by the interweaving of several melodic lines. The lines are independent but sound together harmonically. Contrasting terms are homophony, wherein one part dominates while the others form a basically chordal accompaniment, and monophony, wherein there is but a single melodic line (e.g., plainsong). Polyphony grew out of the practice of organum, in which a plainsong melody is paralleled by another melody at the interval of a fourth or a fifth. This practice, first described in the Musica enchiriadis (late 9th cent.), developed into freer forms of countermelody, culminating in the great age of polyphony in the 15th and 16th cent. In the music of this period, harmonies seem to be generated by the melodic lines sung simultaneously. The gradual ascendancy of harmonic relationships over melodic considerations and the resultant development of major and minor tonalities led in the baroque era to a polyphony controlled by harmony. The fugues and chorale settings of J. S. Bach are the epitome of this type. Homophonic texture is more characteristic of the music of the classical and romantic eras, but in the 20th cent. there has been renewed interest in polyphonic aspects of musical texture and structure. See counterpoint.