An archaic or alternative form of 'œuvre' (a work or artistic creation), rarely used in modern English.
From Old French 'oeuvre' via Latin 'opera' meaning work. This spelling represents an earlier English transliteration before the modern 'œuvre' became standardized.
This is a perfect example of English trying and failing to adopt French words smoothly—we had 'doeuvre,' then 'oeuvre,' then finally settled on using 'œuvre' with the fancy ligature, which most English speakers still can't type.
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