Unrhymed Japanese poetic form consisting of 17 syllables arranged in three lines containing five, seven, and five syllables, respectively.
Haiku expresses much and suggests more in the fewest possible words. The form gained distinction in the 17th century, when Basho elevated it to a highly refined art. It remains Japan's most popular poetic form. The Imagist poets (1912–30) and others have imitated the form in English and other languages.