"Trepak" is one of the several consecutive ethnic dances in Pyotr Ilyich Tchaikovsky's famous ballet The Nutcracker. It is based on the traditional Ukrainian folk dance known in Ukrainian as the Tropak or Tripak.
The "Trepak" often also goes under the name "Russian Dance" (the other ethnic dances of the ballet have dual names as well, e.g. "Tea" is also "Chinese Dance"). The "Trepak" is arguably the most popular dance of the ballet (although a case could be made for both the "Dance of the Sugar Plum Fairy" and the "Waltz of the Flowers", which are heard more often than the "Trepak"). The dance makes much use of ethnic Ukrainian folk melodies.
Usage examples of "trepak".
In the middle of the room a short handsome general with a red face was dancing the trepak with much spirit and agility.
Kovalev, and in his joy he nearly burst into a trepak all around the room, but Ivan hindered him by coming in.