比喻曾遭受挫折，後遇類似狀況就變得膽小如鼠。如：「他因曾經考試不及格，被化學老師罰站，所以只要一聽到要考化學，就直冒冷汗。真是『一朝被蛇咬，十年怕草繩』。」亦作「一度著蛇咬，怕見斷井索」。

When something or someone has hurt you once, you tend to avoid that thing or person; it means when you have had an unpleasantexperience you are much more careful to avoid similar experiences in the future.

“I once sent in money for something I saw advertised in the back of a magazine, but the merchandise was of such poor quality I was sorry I’d bought it. I’ll never buy anything that way again; once bitten, twice shy."

If you fall in love with someone and that someone rejects or hurts you – once bitten – you may be very, very reluctant – twice shy – to let yourself fall in love again.