Wiktionary
n. A label sold by charities in form of a cinderella stamp to raise funds.
Wikipedia
A charity label is a label resembling a postage stamp, sold by charities to raise funds. They are generally intended to be used on mail, as a way of advertising the sender's support of the charity's cause.
Christmas Seals and Easter Seals are perhaps the two best-known types, although many kinds have been made.
While designed to look like postage stamps, they only rarely include a denomination, and never the name of a country. They are distinct from charity stamps which also include a charge for postage.
Charity labels are one of several kinds of cinderella stamp.
Messina earthquake stamps.jpg|Italy 1908, Messina earthquake charity labels Presidency War and Relief Fund half anna charity label 1916.jpg|India 1916, Bombay Presidency War and Relief Fund half anna charity label 1916, 10 kopecks War victims charity label of Fellin