The term for the first stanza of a renga that later became independent haiku is hokku. In a traditional renga, hokku is the opening 5–7–5 sound-unit verse, and it establishes the gathering’s setting, season, and tone before the other poets add linked stanzas.
The hokku had a special status within collaborative poetry. It was often composed by an honored guest and was expected to acknowledge the occasion and surroundings. Unlike later linking verses, it could stand relatively well on its own, helping prepare the way for independent short poems.
By the time of Matsuo Bashō in the 17th century, hokku increasingly appeared outside renga, including in haibun and haiga. In the late 19th century, the Meiji-era poet Masaoka Shiki renamed the standalone form haiku. The word hokku remains useful when referring to the opening verse of a renga or renku sequence. A common mix-up is senryū: it shares the short three-part shape but traditionally focuses more on human behavior and humor than seasonal nature.