aerugo
noun
ae·ru·go
ēˈ-rü-(ˌ)gō,
i-,
ī-
plural -s
: the rust of a metal and especially brass or copper : verdigris
Word History
Etymology
Middle English erugo "mildew, plant rust," borrowed from Medieval Latin, going back to Latin aerūgō "verdigris," from aer-, aes "bronze, brass, copper" + -ūgō, suffix marking a surface layer or discoloration
First Known Use
1664, in the meaning defined above