Fenya (fenia, феня) or fenka (fenjka, фенька) is a Russian cant language used among criminals. Originally it was a cryptolanguage of ofenyas or ofenes, old Russian peddlers, and had a number of names or it might come from the Russian word фен or fen which is the west wind. There are no convincing explanations about the origins of the words "ofenya" and "fenya". In modern Russian language it is also referred to as blatnoy language (Russian: блатной язык), where "blatnoy" is a slang expression for "criminal". It is also widely used in "thieves' songs".
The grammar of fenya is Russian; the vocabulary has changed over time.
The original fenya consisted of broken Russian words borrowed from Greek and other foreign languages. Vladimir Dahl in his Explanatory Dictionary of the Live Great Russian language gives the following examples:
Also, fenya included usual Russian words in unusual meanings, like шаблон shablon (template) for military or police headwear, педаль pedal for cellphone (recent addition).
The vocabulary changed over time, with notable infusion of words of Yiddish origin. During the times of the Soviet Union fenya penetrated into common spoken Russian and can no longer be considered cryptic, although it is still commonly associated with those who have connections to the Russian criminal culture or who have spent a significant amount of time incarcerated.
A number of explanations for this phenomenon are suggested. For one, a significant part of the population, not necessarily criminals, went through labor camps, and massive indiscriminate amnesties after the death of Joseph Stalin resulted in a penetration of the subculture of convicts into everyday life in the form of a shock wave. Particularly, many writers, poets, and journalists who had been arrested began to use fenya in their work after release. Another reason comes from the fact that criminal life was romanticized in popular culture: for example, in the form of "blatnaya song", see Shanson. Few "common" Russians possess a complete or even complex understanding of fenya and fewer still - for various reasons - will admit to it.