One who is particularly cunning, conniving, shifty, sneaky, scheming and down right sly. Weasels are known for their ability to adapt to any situation and to manipulate it to suit their own weasel ways. In other words, my brother Beau.
When used in regard to a female weasel, "weaselette" should be used.
Also used as a verb (ie. to weasel) and as an adjective (eg. weaselish)
"Tell me of your latest weaselish escapades, brother"
"Beau, you are a true weasel!"
"How are you going to weasel your way out of this one?"
"Beware of the weasel"
"Do teach me in the ways of the weasel"