Just to be encyclopedic - I can say that "chicken" was a 17th - 18th century colloquialism for a weak or feeble creature or - perhaps ironically looking at the last sentence - one of "mean spirit".
- And on a brighter note, one of the great Australasian gifts to the English language is the term "chook" which implies a certain affection for the bird - even while eating it. AlanE 16:48, 30 October 2012 (EDT)