Terminology
The English word "weasel" was originally applied to one species of the genus, the European form of the least weasel (Mustela nivalis). This usage is retained in British English, where the name is also extended to cover several other small species of the genus. However, in technical discourse and in American usage, the term "weasel" can refer to any member of the genus, or to the genus as a whole. Of the 17 extant species currently classified in the genus Mustela, ten have "weasel" in their common names. Among those that do not are the stoat, the polecats, the ferret, and the European mink (the superficially similar American mink is now regarded as belonging in another genus, Neovison).
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