How has it come to pass that the weasel is synonymous with treachery or dishonesty? It seems to exist only in 'weasel words' in the U.K. but evidently it is a noun for a traitor in the U.S.

Here's more on the term, Fred.

http://www.acsu.buffalo.edu/~insrisg/nature/nw99/weasels.html

Mozart56. Thanks for that interesting link.Around here weasels are regarded as useful ( and straightforward ) predators, so the use of the word in that way was puzzling.