Cviček is a Slovenian wine from the Lower Carniola region of Slovenia, composed of various grapes: Modra Frankinja (Blue Franconian), Žametna Črnina and Kraljevina, and occasionally Laški Rizling (Italian Riesling) is also added. Modra Frankinja gives it its full flavour, Žametovka makes it drinkable and adds to its acidity, while Rdeča Kraljevina as one of white sorts regulates its alcohol level (from 7.5 to maximum 10% alcohol) and provides the wine with an agreeable gentleness.
In the Middle Ages the Lower Carniola was a constituent part of the March of Carniola, and its wine was named Marvin (from German Marwein from Markwein), which was also mentioned by Valvasor, a seventeen-century Slovenian historian. With the abolition of old viticultural system, people started to neglect vineyards, vine decay grew larger and larger and concomitantly, wine quality started to drop gradually. Becoming more and more sour, people referred to it as cviček (an old Slovenian word denoting very sour wine) and somehow the name stuck, allegedly also because of the synonymous German expression zwikt.
It is common for Cviček to have a characteristic acidity; this, however, does not necessarily imply it has to be too sour. Nevertheless, it would be inappropriate to make it sweeter in order to gain wider acceptance.