Eruginous

Part of speech: adjective

Definitions

1. characterized by a greenish or bluish hue that often results from the corrosion of copper-containing materials
2. referring to the distinctive green or blue discoloration caused by the oxidation of copper surfaces
3. having a green or bluish tint typically associated with corrosion on copper and similar metals

Etymology: Latin "aes" meant copper, bronze or brass, and the word "aerūgō" was a formation from it meaning rust, specifically the green crust that forms on copper. That crust is what gave the adjective its sense. The Latin "aerūginōsus" meant something like "rusty" or "covered in that green coating", built from "aerūgō" plus the suffix "-ōsus", which turns a noun into an adjective meaning "full of" or "characterised by" the noun. The word came into English by way of French. Middle French had "erugineux", meaning "verdigris-coloured", and English also took the term directly from Medieval Latin, where "aerūginōsus" had shifted towards the sense "rust-coloured". So the English form descends from both routes, and the spelling "eruginous", with the initial "ae" simplified to "e", is an alternative of the same word.

Synonyms: greenish, verdigris, rusty, oxidized