Definition of "byock"

A noticeable feature of the sales was the quantity of fine goods, principally of white and feminas. The best white qualities and good broken brought 10 per cent. to 15 per cent. advance, while other qualities sold firmly. White and light femina were also 10 to 15 per cent. dearer, principally for the best lines. Dark femina and byocks were 10 per cent. higher.

1899 September 8, “The Ostrich Feather Market”, in Democrat and Chronicle, 67th year, Rochester, N.Y., page 15, column 5

3.—Wing-Quills or Remiges; Whites and Feminas.—The wing-quills are the largest feathers in the wing, and are arranged in a single row. They include the “Whites” in the cock, and the “Feminas” in the hen, as well as the “Byocks” or “Fancies” in the cock.

1909, Agricultural Journal of the Cape of Good Hope, page 514

The usual kinds of ostrich feathers known to the trade come into the Tripoli market. These are whites, blacks, feminas, byocks, spadonas, boos, drabs and floss.

1909 August 12, “Ostrich Feathers of Tripoli”, in Neenah Daily Times, volume 53, number 8,451, Neenah, Wis., Menasha, Wis., column 5