Undecuple meter or undecuple time is a musical meter in which each measure is divided into 11 equally spaced beats, usually notated as either 11
4 or 11
8. It is usually subdivided into groupings of two or three beats (for example, a grouping of the meter could be 2+2+2+2+3).
The meter remained largely unused until the 19th century, when Nikolai Rimsky-Korsakov used it in his operas The Snow Maiden and Sadko.
Because 11 is a prime number, undecuple meter is considered a complex time signature. It can be found in jazz, pop, and rock music.