WEREWOLF, n. A wolf that was once, or is sometimes, a man. All
werewolves are of evil disposition, having assumed a bestial form to
gratify a beastial appetite, but some, transformed by sorcery, are as
humane and is consistent with an acquired taste for human flesh.
Some Bavarian peasants having caught a wolf one evening, tied it
to a post by the tail and went to bed. The next morning nothing was
there! Greatly perplexed, they consulted the local priest, who told
them that their captive was undoubtedly a werewolf and had resumed its
human for during the night. "The next time that you take a wolf," the
good man said, "see that you chain it by the leg, and in the morning
you will find a Lutheran."
-- Ambrose Bierce, "The Devil's Dictionary"