Originally, kyoku were the same as senryu (humorous or ironical haiku), but after the death of Senryu the first (a poet), and during the time of Senryu the fourth, poems in the Senryu style were named 'haifu kyoku'.
本来、川柳と同じもので、初代川柳没後、四世川柳の代に、川柳風の作品に「俳風狂句」と名づけたのがはじまり。