old wives' tale

In this context, the word “wives” means “women” and not “married women,” retaining the original sense of Old English wīf, which meant “woman” as well as “wife”. The phrase could be a reformation of Old English ealdra cwēna spell or a calque of Latin anīlis fābula, both literally “old women’s story.”

old wives' tale (plural old wives' tales)

1. A supposed truth that has been passed down by word of mouth
2. A rumour, myth or superstition; something which is almost certainly untrue, despite acceptance by many.

• old wife
• urban legend
• urban myth