ordinary verse of a renga
In renga (linked verse), a 平句 is any verse that is not the first three (発句, 脇句, 第三) or the last (挙句). It is a technical term used in classical poetry contexts.
In renga, verses other than the hokku, wakiku, daisan, and ageku are called hiraku.
From 平 (hira, 'ordinary, flat') + 句 (ku, 'verse, phrase'). The exact historical derivation is uncertain, but the term is conventionally associated with the non-special verses in renga.