Haiku (called hokku until the Nineteenth Century) - Japanese verse usually employing allusions and comparisons. The verse is composed of three lines containing a fixed number of syllables, usually 17 or 19, within three unrhymed lines: five, seven, and five syllables per each line in order. The haiku presents a pair of contrasting images, one suggestive of time and place, the other a vivid but fleeting observation which, together, evoke mood and emotion.
The following example is from Basho (pseudonym of Matsuo Munefusa 1644–94):
Now the swinging bridge
Is quieted with creepers . . .
Like our tendrilled life.
The word evolved from renga, used extensively by Zen Buddhist monks in the Fifteenth and Sixteenth Centuries.