wea·sel 
(w
ēz
əl)
n.1. Any of various carnivorous mammals of the genus Mustela, having a long slender body, a long tail, short legs, and brownish fur that in many species turns white in winter.
2. A person regarded as sneaky or treacherous.
intr.v. wea·seled,
wea·sel·ing,
wea·sels also
wea·selled or
wea·sel·ling To be evasive; equivocate.
Phrasal Verb: weasel out Informal To back out of a situation or commitment in a sneaky or cowardly manner.
[Middle English wesele, from Old English wesle.]

weaselermine in brown summer phase
Mustela erminea