Sheffield plate
noun /ˌʃefiːld ˈpleɪt/
/ˌʃefiːld ˈpleɪt/
[uncountable]- a type of metal consisting of copper (= a soft red-brown metal) covered with a thin layer of silver. The method of covering copper objects with silver and then heating them to keep it in place was invented by Thomas Boulsover in Sheffield in the 1740s. It became an important industry because objects could be made of Sheffield plate much more cheaply than if they were made of silver.