What is "butautas"

Butautas (baptized Henryk; died on May 7, 1380 in Prague) was a son of Kęstutis, Grand Duke of Lithuania. He attempted to depose his uncle Algirdas and usurp power in Lithuania, but failed and was forced into exile. He joined the court of the Holy Roman Emperor and even inspired a poem about conversion to Christianity. Butautas is sometimes confused with his brother Vaidotas.