From Old English stempan 'to pound' — the postage stamp was invented in 1840 with the Penny Black.
A small adhesive piece of paper affixed to a letter to show postage has been paid; also, a device for imprinting a mark.
From Old English stempan 'to pound, stamp,' from Proto-Germanic *stampōną, possibly from PIE *stemb- 'to stamp.' The postal stamp sense dates from 1840, when Rowland Hill introduced the Penny Black — the world's first adhesive postage stamp. Key roots: *stemb- (Proto-Indo-European: "to pound, stamp (uncertain)").