What is "krutnava"

'' Krútňava'' (abroad staged as The Whirlpool or Katrena after the main female role) is an opera in six scenes by Eugen Suchoň written in the 1940s to a libretto by the composer and Štefan Hoza, based on a novella, '' Za vyšným mlynom (Beyond the Upper Mill)'' by Milo Urban. The opera was premiered at the Slovak National Theatre, Bratislava, on 10 December 1949.