Definition of "haiku"

haiku

/ˈhaɪ.kuː/

noun
plural haiku or haikus
1. A Japanese poem in three lines, the first and last consisting of five morae, and the second consisting of seven morae, usually with an emphasis on the season or a naturalistic theme.
  Quotations
  Some of the results resemble haikus.
  2009 January 25, Colin Moynihan, “A Project Documents Inauguration Day, in Washington and Across the Globe”, in New York Times‎
2. A three-line poem in any language, with five syllables in the first and last lines and seven syllables in the second, usually with an emphasis on the season or a naturalistic theme.