What is "contour feathers"

Contour \Con*tour"\, n. [F. contour, fr. contourner to mark the outlines; con- + tourner to turn. See Turn.]

1. The outline of a figure or body, or the line or lines representing such an outline; the line that bounds; periphery.

   Titian's coloring and contours.
   --A. Drummond.

2. (Mil.) The outline of a horizontal section of the ground, or of works of fortification.

   Contour feathers (Zo["o]l.), those feathers that form the general covering of a bird.

   Contour of ground (Surv.), the outline of the surface of ground with respect to its undulation, etc.

   Contour line (Topographical Suv.), the line in which a horizontal plane intersects a portion of ground, or the corresponding line in a map or chart. [1913 Webster] ||

n. (contour feather English)