The Qu form of poetry is a type of Classical Chinese poetry form, consisting of words written in one of a number of certain, set tone patterns, based upon the tunes of various songs.
Thus Qu poems are lyrics with lines of varying longer and shorter lengths, set according to the certain and specific, fixed patterns of rhyme and tone of conventional musical pieces upon which they are based and after which these matched variations in lyrics (or individual Qu poems) generally take their name.
In Chinese literature, the Qu (Chinese: 曲; pinyin: qǔ; Wade–Giles: ch'ü) form of poetry from the Yuan Dynasty may be called Yuanqu (元曲 P: Yuánqǔ, W: Yüan-ch'ü).
Both Sanqu and Ci are lyrics written to fit a different melodies, but Sanqu differs from Ci in that it is more colloquial, and is allowed to contain Chenzi (襯字 "filler words" which are additional words to make a more complete meaning).
Sanqu can be further divided into Xiaoling (小令) and Santao (散套), with the latter containing more than one melody.