a strip of material gathered or pleated and attached at one edge, with the other edge left loose or hanging: used for trimming, as on the edge of a skirt or sleeve or on a curtain, slipcover, etc.
"wide ruffle," 1713, from M.E. frounce "pleat, wrinkle, fold" (late 14c.), from O.Fr. fronce "fold, gather, wrinkle," from Frankish *hrunkja "wrinkle," of unknown origin. Influenced in form by flounce (v.).
flounce 1 (flouns) n. A strip of decorative, usually gathered or pleated material attached by one edge, as on a garment or curtain. tr.v.
flounced, flounc·ing, flounc·es To trim with a strip or strips of gathered or pleated material.
[Alteration of frounce, from Middle English, pleat, from Old French fronce, of Germanic origin; see sker-2 in Indo-European roots.]