Webster’s Revised Unabridged Dictionary · 1913
Swan's-down
Swan's′-down′, or 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.