frounce (v.) Look up frounce at Dictionary.com
c. 1300, "to gather in folds," from Old French froncir, froncier "to pleat, fold; purse; crease, wrinkle," from fronce (n.), which is of unknown origin. Perhaps it is somehow from Latin frons "forehead," on the notion of frowning. Related: Frounced; frouncing.