Wiktionary
n. (context musici English) An old folk Russian wind instrument of the end-blown flute type.
Wikipedia
Swirel is an old folk Russian wind instrument of the end-blown flute type. Classification: Aerophone-Whistle Flute-recorder. In the Old Rus' this instrument was made either of hollow reed or cylindrical wood branches. A legend says that Lel', son of the Slavic goddess of love Lada was a svirel player. In spring he would make his svirel of birch branches.
Traditional Russian svirel has not yet been studied well enough. Specialists have long tried to relate the present day’s pipe instruments to their Old Russian names. Most often the chroniclers used three names for this type instruments: svirel, sopel ( sopilka) and tsevnitsa.