Stilyagi is a Russian word generally translated as, "style-hunter". The term was used to describe lovers of jazz in the USSR from the end of WWII till the mid-fifties. These individuals displayed their freedom by making a political statement through their embrace of what they thought American jazz culture was.

Charles Paul Freund describes their attributes in his article, "In Praise of Vulgarity":

"They wore jackets with huge, padded shoulders and pants with narrow legs. They were clean-shaven, but they let their hair grow long, covered it with grease, and flipped it up at the back. They sported unusually colorful ties, which they let hang well below their belts.... Women wore short, tight skirts and heavy lipstick."
While their idea of an American jazz fan was a little off, the stilyagi of the early fifties ignored Stalin's ban on jazz music, and lead the way for other stilyagi who did the same with rock and punk music.

Timeshredder pointed out an alternative use of the term: "Robert Heinlein used the term in The Moon is a Harsh Mistress to designate the street urchins of the space colonies. It has also been adopted by a Michigan-based SF social club."

Source: "In Praise of Vulgarity", Reason Magazine, March 2002