to wrinkle, curl, or form into frounces (folds or pleats); to pleat or crease.
From be- + frounce, where frounce is an archaic word for a fold, pleat, or wrinkle, possibly from French 'froncer.' Extremely rare in modern English.
Befrounce is one of those words that probably hasn't been used sincerely in over a century—it's a linguistic fossil showing how English speakers once loved to combine be- with almost any noun or adjective.
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