In Belarusian the word literally means low quality hay, when indigent farmers mix (shake: трасуць, trasuts) fresh grass with the yesteryear's dried hay. The word acquired the second meaning ("language mixture") relatively recently (probably around the time of the collapse of the USSR), although it had been already known as a phenomenon. Zianon Pazniak is often said to be the one who has popularized the use of the word for the Belarusian-Russian language mixture (see Pozniak, 1988). However, not all inhabitants know its metaphorical meaning or even the word as such. In the Belarusian-Russian borderland, at least, the same phenomenon is not called "trasianka" (local population does not usually know the word). "Meshanka" is the expression most often used there instead of "trasianka" (this information is based on an interdisciplinary research carried out in the district of Horki and Drybin in 2004).
The phenomenon of mixing the Belarusian and Russian language, which is nowadays called "Trasianka", is older than the name itself and has relatively long history. A piece of evidence can be found, for example, in the 19th-century play by Wincent Dunin-Marcinkiewicz (Vintsent Dunin-Martsinkevich) The Gentry of Pinsk (see the 1984 edition). Although it is a piece of art and not a record of everyday speech, it can be assumed that it reflects real language use (in certain situations with certain types of people) of that time. Reports on Belarusian-Russian language mixing can be found in various written documents from the beginning of the 20th century (e.g. in the Nasha Niva newspaper).
Trasianka is the kind of language typically spoken by villagers in Belarus whose first acquired language is Belarusian, but who abandoned it in favor of Russian, seeing Russian as more "urban," "fashionable," or "civilized." Thus they ended up speaking this "mixture" (interlanguage, see Liskovets, 2002). Trasianka may be heard also in the cities of Belarus, where it is spoken by older and some middle-aged people, usually former migrants from villages to cities. Some educated (older or middle-aged) people, for example, the Belarusian president Lukashenko (esp. in the mid-1990s) or the minister of agriculture (observed in 2005) also speak trasianka. It seems that it is an unstable language formation, the spread of which might reduce in the future, as younger generations do not speak it.
There are certain social problems with speaking in Trasianka, especially the issue of generation gap that Trasianka and literary Belarusian create between parents and children, and the rejection and alienation that has been experienced by some nationalistic activists who insist on using correct literary Belarusian. However, for other intellectuals whose education is connected to national culture (these are among philologists, linguists, historians, culturologists, ethnologists etc.), trasianka is not acceptable in formal communication either. Also in general it is valued low as a "spoiled", "corrupted" Belarusian or Russian. There are several comedians in Belarus (esp. Sasha and Sirozha) who use Trasianka in their comic skits.
Trasianka speakers use mostly Russian vocabulary, but preserve the phonetical features of Belarusian. Grammar seems to be combined, Belarusian-Russian. Although it does have its structural regularities, Trasianka is relatively variable and presents rather a linguistic continuum between Belarusian and Russian than a discrete linguistic system.
There is a similar sociolinguistic phenomenon in Ukraine, an Ukrainian–Russian language mixture that is called surzhyk. Overall, trasianka was ignored by the mainstream linguists and sociologists in Belarus and abroad until the 1990s when the first articles which explicitly deal with trasianka started to appear (cf. the references below). In older linguistic literature, the phenomenon is dealt with under the heading "language cultivation" ("kul'tura movy"), "linguistic interference" etc.