5-7-5 syllable pattern
Refers to the metrical form of haiku, senryū, and similar verse, consisting of three phrases with 5, 7, and 5 morae respectively.
Haiku are composed in seventeen syllables in a 5-7-5 pattern.
This senryū has a pleasant 5-7-5 rhythm.
From the numbers 五 (five), 七 (seven), and 五 (five), directly describing the syllable count of the verse form.