Haiku (俳句, ?) is a mode of Japanese poetry, the late 19th century revision by Masaoka Shiki of the older hokku (発句, hokku?), the opening verse of a linked verse form, haikai no renga. The traditional hokku consisted of a pattern of approximately 5, 7, and 5 morae, phonetic units which only partially correspond to the syllables of languages such as English. It also contains a special season word (the kigo) representative of the season in which the renga is set, or a reference to the natural world.