"Raining cats and dogs" means it's raining a whole whole lot, and it's coming down hard.

It is possible that the "cat" bit of the phrase is derived from the Latin word "catadupe," or the French "catadoupe," each meaning "waterfall." Or the phrase might be a bastardization of the Greek "cata doxas," literally, "contrary to experience," also meaning an unusual amount of rain. It is also a possibility that I am making this up as I go along. But I'm not.

The phrase might be a corruption of the old Pennsylvania Dutch saying "raining cats and ducks," cats meaning witchcraft, ducks meaning rain. Makes a little sense - witches + rain = lots of extra-bad rain.

Or, the source could be mythological. Sailors from many cultures consider cats to have influence over storms, and English sailors still say a cat "has a gale of wind in her tail" when it is unusually frisky. In the Harz mountains, the stormy northwest wind is called "the cat's nose." Dogs have long been symbols of storms. Odin, the Norse storm god, is often described as having both dog and cat companions. In old German illustrations, the wind is depicted as the head of a dog or wolf.

The phrase first appeared (in its present form) in 1738, in Jonathan Swift's   A Complete Collection of Polite and Ingenious Conversation:   "I knew Sir John will go, though he was sure it would rain cats and dogs." A variant form occurred as far back as 1653, playwright Richard Brome's City Wit:   "It shall raine ... Dogs and Polecats."   We're not sure what that one means.

It has also been seriously suggested that, a long time ago, British streets were drainage-less and so poorly constructed that many cats and dogs would drown whenever there was a storm. People seeing the corpses floating by would think they had fallen from the sky, like biblical rains of frogs and locusts. Michael B. Quinion destroys this theory best: "If you'll believe that, I would suggest you are both credulous and unobservant of the speed at which both cats and dogs can move to get out of the weather."

Whirlwinds can do some weird stuff. We all know about the frogs and bugs. There one account of a "fish fall" in India in which people found fish weighing up to eight pounds. There have been instances of rains of fish, frogs, grasshoppers, and ice-coated ducks, but there is as yet no account of a rain of cats and dogs.

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