Simple past tense and past participle of cooper.(verb)
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Use "coopered" in a sentence
"This wine is 94% merlot with 4% cabernet sauvignon and 2% cabernet franc and it was aged for 14 months in French-coopered"
"When I read Ursula Leguin's Earthsea books again recently I noticed each and every time Ged was described as "brown", "dark", "coopered", and I noticed how she makes a point of singling out "white" characters as minorities in her imagined world."
"After MM03, they coopered up their calculations with a re-collation of the data."