[Ariii]

A slavic dragon is any dragon in Slavic mythology, including the Russian zmei (or zmey; змей), known in the Ukraine as zmiy (змій), and its counterparts in other Slavic cultures: the Bulgarian zmei (змей), the Polish zmiy (żmij), the Serbian and Croatian zmaj (Serbian: змај, Croatian). The Romanian zmeu is also a slavic dragon, but a non-cognate etymology has been proposed. These may also be rendered as "serpent" in English translations.

The Polish smok (e.g. Wawel Dragon of Kraków) is also known in parts of Ukraine or Belarus as smok (смок), tsmok (цмок), can also be included. The smok according to some Slavic traditions is also an ordinary snake which may turn into a zmei with age.
The terms smok ("serpent") and tsmok ("sucker") can signify a dragon, but also just an ordinary snake. There is Slavic folklore in which a snake (which is called smok) when it reaches a certain age grows into a dragon (zmaj, etc.). Similar lore is widespread across Slavic countries.
The folklore that that an ancient snake grows into a dragon is fairly widespread in Slavic regions. This is paralleled by similar lore in China.[a]

In Bulgaria is a similar folk belief that the smok, which starts out as a non-venomous snake, grows to become a dragon after living 40 years.[5]

There are also among the East Slavic folk the tradition that a viper transforms into a dragon.[6] Among Ukranians the lore is that the viper needs 7 years to metamorphosize into a dragon, among Belorussians, the requisite time is 100 years, according to one comparison.[6]

The weather-making dragon, ismeju, of Romanian Scholomance folklore is also locally believed to grow out of a snake which has lived for 9 years (belief found at "Hatzeger Thal" or Hațeg).[7]