u-Tack [noun] [U] [trademark] - a soft sticky substance used for temporarily fixing something to a surface, esp. something light to a wall. It can be used more than onceHelga used Blu-Tack to put some posters up on her bedroom wall.See picture: Stationery
BL
Meaning of BL in English
Cambridge English vocab. Кембриджский английский словарь. 2012