the.com/decal

means A design printed on special paper or film so it can be transferred onto another surface, like glass, metal, or skin.

from Short for 'decalcomania,' a 19th-century craze (the French called it décalcomanie, from décalquer, 'to transfer a tracing') where hobbyists transferred colorful printed images onto furniture, china, and keepsakes. English speakers eventually got lazy with the fancy word and clipped it down to the snappy 'decal' we use now.