n. & v.
n. 1 the rough silk enveloping a silkworm's cocoon. 2 untwisted silk thread used in embroidery. 3 = dental floss.
v.tr. (also absol.) clean (the teeth) with dental floss. floss silk a rough silk used in cheap goods.
[ F (soie) floche floss(-silk) f. OF flosche down, nap of velvet ]