animal membrane used to separate sheets of gold that are being hammered into gold leaf
goldbeater's skin in American English
(ˈɡouldˌbitərz)
noun
the prepared outside membrane of the large intestine of the ox, used by goldbeaters to lay between the leaves of the metal while they beat it into gold leaf
Word origin
[1700–10; gold + beater + 's1]This word is first recorded in the period 1700–10. Other words that entered Englishat around the same time include: camera, cirrus, emphatic, hump, sliding scale