The Collaborative International Dictionary of English v.0.48:
Floss \Floss\ (?; 195), n. [It. floscio flabby, soft, fr. L.
fluxus flowing, loose, slack. See Flux, n.]
1. (Bot.) The slender styles of the pistillate flowers of
maize; also called silk.
2. Untwisted filaments of silk, used in embroidering.
3. A body feather of an ostrich. Flosses are soft, and gray
from the female and black from the male.
[Webster 1913 Suppl.]
Floss silk, silk that has been twisted, and which retains
its loose and downy character. It is much used in
embroidery. Called also floxed silk.
Floss thread, a kind of soft flaxen yarn or thread, used
for embroidery; -- called also linen floss, and floss