What is "polyrhythm"

1911, probably a back formation from polyrhythmic.

n. (context music English) Multiple rhythmic elements being performed simultaneously.

Polyrhythm is the simultaneous use of two or more conflicting rhythms, that are not readily perceived as deriving from one another, or as simple manifestations of the same meter. The rhythmic conflict may be the basis of an entire piece of music ( cross-rhythm), or a momentary disruption. Polyrhythms can be distinguished from irrational rhythms, which can occur within the context of a single part; polyrhythms require at least two rhythms to be played concurrently, one of which is typically an irrational rhythm.

is Perfume's second single from their second album Game and 10th overall, as well as the first track on their third compilation album Love the World. Appropriately, the song's bridge is polyrhythmic, incorporating 5/8, 6/8 in the vocals, common time (4/4) and 3/2 in the drums. Tokuma Japan Communications originally requested for the bridge of the song to be removed for its atypical nature; a concession was reached by including a radio edit known as the "Extra Short Edit" on the single, which removes the bridge while the vocoded backing vocal on the near-end of the song (at 3:02) is half-distorted. The song was used for the Kankyō Recycle Campaign by NHK. The single has 2 editions: a CD only version and CD+DVD version. The only difference between the CD and CD+DVD version is that the CD+DVD version has the music video of Polyrhythm.

Polyrhythm appears in Konami's Dance Dance Revolution and pop'n music arcade music games (covered by Pink Lemonade), as well as Namco's Taiko no Tatsujin. Former Megadeth guitarist Marty Friedman also released his own version of the song on his album Tokyo Jukebox. The song appeared in the film and soundtrack for the Pixar film Cars 2. The director, John Lasseter, was happy to see the girls there and said "The moment I listened to Polyrhythm, I loved it, it was like falling in love."