Haiku is a very short form of Japanese poetry typically characterised by three qualities:
- The essence of haiku is "cutting" (kiru). This is often represented by the juxtaposition of two images or ideas and a kireji ("cutting word") between them, a kind of verbal punctuation mark which signals the moment of separation and colors the manner in which the juxtaposed elements are related.
- Traditional haiku consist of 17 on (also known as morae), in three phrases of 5, 7 and 5 on respectively.
- A kigo (seasonal reference), usually drawn from a saijiki, an extensive but defined list of such words.
Modern Japanese haiku are increasingly unlikely to follow the tradition of 17 on or to take nature as their subject, but the use of juxtaposition continues to be honored in both traditional and modern haiku. There is a common, although relatively recent, perception that the images juxtaposed must be directly observed everyday objects or occurrences.
In Japanese, haiku are traditionally printed in a single vertical line while haiku in English often appear in three lines to parallel the three phrases of Japanese haiku.
Previously called hokku, haiku was given its current name by the Japanese writer Masaoka Shiki at the end of the 19th century.
Today, haiku are written in many languages, but most poets outside of Japan are concentrated in the English-speaking countries and in the Balkans.
It is impossible to single out any current style or format or subject matter as definitive. Some of the more common practices in English are:
- Use of three (or fewer) lines of 17 or fewer syllables;
- Use of a season word (kigo);
- Use of a cut (sometimes indicated by a punctuation mark) paralleling the Japanese use of kireji, to implicitly contrast and compare two events, images, or situations.
While the traditional Japanese haiku has focused on nature and the place of humans in it, some modern haiku poets, both in Japan and the West, consider a broader range of subject matter suitable, including urban contexts.
Brian P. Cleary's "Report Card" provides an excellent example of contemporary American haiku for children:
Four days of the year,
One tiny piece of paper
Turns my stomach sour.
The loosening of traditional standards has resulted in the term "haiku" being applied to brief English-language poems such as "mathemaku" and other kinds of pseudohaiku. Some sources claim that this is justified by the blurring of definitional boundaries in Japan.