cold feet, to get/have

To be timid; to back off from some undertaking. This expression appears to date from the nineteenth century, at least in its present meaning. In the early seventeenth century it was an Italian proverb that meant to have no money; it was so used by Ben Jonson in his play Volpone. The source of the more recent meaning is obscure. Some believe it comes from soldiers retreating in battle because their feet are frozen. Another source cites a German novel of 1862 in which a card player with- draws from a game because, he claims, his feet are cold.