Haiku (俳句, Haiku?) listen (help·info) is a form of Japanese poetry. Previously called hokku, it was given its current name by the Japanese writer Masaoka Shiki at the end of 19th century. Shiki suggested haiku as an abbreviation of the phrase "haikai no ku" meaning a verse of haikai[1]. A hokku was the opening verse of a linked verse form, renku (haikai no renga). In Japanese, hokku and haiku are traditionally printed in one vertical line (though in handwritten form they may be in any reasonable number of lines). In English, haiku are usually written in three lines to equate to the three metrical phrases of a haiku in Japanese that consist of five, seven, and five on (the Japanese count morae, which differ from English-language syllables; for example, the word "haiku" itself counts as three on in Japanese (ha-i-ku), but two syllables in English (hai-ku); writing seventeen syllables in English produces a poem that is actually quite a bit longer, with more content, than a haiku in Japanese). Because Japanese nouns do not have different singular and plural forms, "haiku" is usually used as both a singular and plural noun in English as well. Thus, practicing haiku poets and translators refer to "many haiku" rather than "haikus". Senryū is a similar poetry form that emphasizes irony, satire, humor, and human foibles instead of seasons, and may or may not contain a kigo or a kireji. Haha! Jajá!

@Jura Your little ditty doesn't seem to have the number of syllables that you specify for a haiku; yous has 2, 3 and 4 syllables. Am I missing something significant?

here the german version of your haiku: Der alte Weiher: Ein Frosch springt hinein. Oh! Das Geräusch des Wassers. another one I like: Das neue Jahr: Winde aus alten Zeiten Machen mir Zahnweh. (Sarah Kirsch (1991))

kiss the rain...