Quote Originally Posted by gRomoZeka
It can be either an unregulated market in the macroeconomic sense, or an unauthorized marketplace (without an appropriate licence). The example of tiny "стихийные рынки" are babushkas, selling stuff near subway stations. They are not supposed to be there. These markets can be quite big, with dozens or even hundreds of sellers.
What the babushkas are doing sounds like "selling without a permit", see http://ezinearticles.com/?Selling-Perfu ... &id=312354 It appears this may be perfectly legal in the UK, see http://www.dsa.org.uk/legislation.htm