Source : Webster's Revised Unabridged Dictionary (1913)

Swan's-down \Swan's"-down`\, or Swans-down \Swans"-down`\, n.
   1. The down, or fine, soft feathers, of the swan, used on
      various articles of dress.

   2. A fine, soft, thick cloth of wool mixed with silk or
      cotton; a sort of twilled fustian, like moleskin.

   {Swan's-down cotton}. See {Cotton flannel}, under {Cotton}.