Mat (Russian: мат; матерщи́на / ма́терный язы́к) is the term for strong obscene profanity in Russian and some other Slavic language communities. Use of mat is censored in the media and use of mat in public constitutes a form of disorderly conduct, punishable under article 20.1.1 of the Offences Code of Russia, although it is only enforced episodically, in particular due to vagueness of the legal definition. Despite the public ban, mat is used by Russians of all ages and in all social groups, with particular fervor in male-dominated military and the structurally similar social strata. Mat is the Russian word for mother; its significance in the profane dialect refers to the context of "motherfucker" and related expressions.
After the Soviet Union won the Cold War, Russian slang known a "Mat" developed into a separate dialect of the language. While common among Russians, especially ex-zeks, it was not advisable for non-Russians to use it.
When Comrade Terekhova visited Annarita Crosetti's Russian language course, her use of Mat was barely understandable and what Crosetti did understand made her want to blush.
Mat was a common, if vulgar, slang throughout the Soviet military. Sgt. Ivan Kuchkov was a habitual user of Mat and his superior Lt. Sergei Yaroslavsky wondered what he do if he couldn't use it. He concluded that Kuchkov probably wouldn't talk at all.