old wives' tale

An old wives' tale is a well-known belief that is actually just superstition. One old wives' tale you may have heard warns that if you swallow chewing gum, it will stay in your stomach for years.

Bits of advice, warnings, and general community wisdom sometimes turn out to be old wives' tales. These include simple superstitions, like "don't open an umbrella indoors," and easy to believe advice like "if you shave, the hair grows back thicker" or "you'll get arthritis if you crack your knuckles." The term old wives' tale uses the oldest meaning of wife, "woman," and is actually quite derogatory. It comes from the tradition of mothers scaring their children out of unwanted behavior.