As a noun copper
is (
lb) a reddish-brown, malleable, ductile metallic element with high electrical and thermal conductivity, symbol cu, and atomic number 29 or
copper can be (slang|law enforcement) a police officer.
As an adjective copper
is made of copper.
As a verb copper
is to sheathe or coat with copper.
As a proper noun cropper is
for a cropper.