get cold feet

To experience nervousness or anxiety before one attempts to do something, often to the extent that one tries to avoid it. I wasn't nervous until the morning of my wedding, but everyone assured me that I had just gotten cold feet. Good luck getting her out on stage—she always gets cold feet before a performance.

Also, have cold feet. Retreat from an undertaking; lose one's nerve. For example, I got cold feet when I learned the trip involves white-water rafting, or Don't count on including her-she's been known to have cold feet in the past. The origin of this term has been lost. In early 17th-century Italy it meant to be short of money, but that sense has never been used in English. [Late 1800s]

COMMON If you get cold feet or have cold feet about something you have planned to do, you become nervous about it and not sure that you want to do it. My boyfriend got cold feet about being in a committed relationship. Leaving Ireland wasn't easy and I had cold feet about it a couple of times.

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 withdraws from a game because, he claims, his feet are cold.