Terminology
The word "Kvass" derived from Old East Slavic квасъ, kvasŭ, meaning "yeast" or "leaven". Today the words used are almost the same: in Belarusian: квас, kvas; Chinese: 格瓦斯/克瓦斯, géwǎsī/kèwǎsī; Latvian: kvass; Polish kwas chlebowy; Russian: квас, kvas; in Ukrainian: квас/хлібний квас/сирівець, kvas/khlibnyy kvas/syrivets. Except Lithuanian: gira, which means beverage similar to Latvian dzira. In Estonian: kali, which means leaven.
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