This is a list of kigo, which are words or phrases that are associated with a particular season in Japanese poetry. They provide an economy of expression that is especially valuable in the very short haiku, as well as the longer linked-verse forms renku and renga, to indicate the season referenced in the poem or stanza. Until 1873, in the Japanese calendar, seasons traditionally followed the lunisolar calendar with the solstices and equinoxes at the middle of a season. The traditional and contemporary months are approximately one month apart from each other, with the traditional New Year falling between late January and early February. The traditional Japanese seasons are: Spring: 4 February – 5 May Summer: 6 May – 7 August Autumn: 8 August – 6 November Winter: 7 November – 3 February For kigo, each season is then divided into early (初), mid- (仲), and late (晩) periods. For spring, these would be: Early spring: 4 February – 5 March (February・First lunar month) Mid-spring: 6 March – 4 April (March・Second lunar month) Late spring: 5 April – 5 May (April・Third lunar month) Japanese haiku poets often use a saijiki, a book like a dictionary or almanac for kigo. An entry in a saijiki usually includes a description of the kigo itself, as well as a list of similar or related words, and a few examples of haiku that include that kigo. A kiyose is similar, but contains only lists of kigo. Modern saijiki and kiyose are divided into the four seasons and New Year, with some containing a further section for seasonless (muki) topics. Each section is divided into a standard set of categories, each containing the relevant kigo. The most common categories are: The season (時候 jikō) The sky and heavens (天文 tenmon) The earth (地理 chiri) Humanity (生活 seikatsu) Observances (行事 gyōji) Animals (動物 dōbutsu) Plants (植物 shokubutsu) This is a list of both Japanese and non-Japanese kigo. If the kigo is a Japanese word, or if there is a Japanese translation in parentheses next to the English kigo, then the kigo can be found in most major Japanese saijiki.