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

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