What is "kireji"

is the term for a special category of words used in certain types of Japanese traditional poetry. It is regarded as a requirement in traditional haiku, as well as in the hokku, or opening verse, of both classical renga and its derivative renku (haikai no renga). There is no exact equivalent of kireji in English, and its function can be difficult to define. It is said to supply structural support to the verse. When placed at the end of a verse, it provides a dignified ending, concluding the verse with a heightened sense of closure. Used in the middle of a verse, it briefly cuts the stream of thought, indicating that the verse consists of two thoughts half independent of each other. In such a position, it indicates a pause, both rhythmically and grammatically, and may lend an emotional flavour to the phrase preceding it.