Question: what is the etymology of the phrase raining cats and dogs?
Answer: “Cats and dogs” may come from the Greek expression cata doxa, which means “contrary to experience or belief.” If it is raining cats and dogs, it is raining unusually or unbelievably hard. “Cats and dogs” may be a perversion of the now obsolete word catadupe. In old English, catadupe meant a cataract or waterfall.