A valuable fur-bearing animal of the genus Mustela (M. erminea), allied to the weasel; the stoat. It is found in the northern parts of Asia, Europe, and America. In summer it is brown, but in winter it becomes white, except the tip of the tail, which is always black.
- A weasel (Mustela erminea) of northern regions, having a black-tipped tail and dark brown fur that in winter changes to white.
- The commercially valuable white fur of this animal.