Swan's-down
Pronunciation : Swan's"-down`, or; Swans"-down`
Part of Speech : n.
Definition : 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.
Source : Webster's Unabridged Dictionary, 1913