Definition of "flouncing"

A very rich lama and net dress, elegantly embroidered and bordered with rich lama flouncings, trimmed with blond lace, over a rich white satin slip […]

1816, La Belle Assemblée: or, Bell's Court and Fashionable Magazine, page 4

Mantillas are larger than last year, and are generally all worn with a deep flouncing, either of the same material, or of black lace; the mantilla itself is also much trimmed with small ruchings of ribbon, guip and guipure lace, laid on quite flat.

1855, “Mantillas and Shawls”, in Graham's American Monthly Magazine of Literature, Art, and Fashion, volume XLVI, number 4, Philadelphia, Pa.: Abraham H. See, 106 Chestnut Street, page 578