QUESTION: Why are there no words that rhyme with purple, orange or silver?

ANSWER: Clement Wood's Rhyming Dictionary confirms that there are no rhymes for orange and silver, and he offers only this for purple: "chirp'll." It is hard to imagine a lamer rhyme.Horrible birds,

Black, yellow, purple,

If the peck doesn't drive you mad,

The chirp'll.

One initially suspects that purple, orange and silver have no rhymes because they're the words for colors, and someone decided that colors were too special to be rhymeable. But orange comes from French, purple from Latin by way of Old English and silver is original Old English going back to the 5th century A.D.

It's simply an anomaly that these three words can't be rhymed. But not that much of an anomaly. Check the dictionary. Victoria Neufeldt, editor in chief of Webster's New World Dictionary, asks, "Is there a rhyme for purpose? Murpose?"

Which brings up a more profound why question: Why isn't "murpose" a word? Why not "milver"?

James Hartman, a University of Kansas professor who specializes in American pronunciation, points out that words tend to grow out of other words. We don't pick unused constructions of letters, like "lep" or "det," and try to apply some meaning to them. "Making up some absolutely new words is one of the less frequent ways we have of creating new meanings," says Hartman. "Extending old words is more typical, or we borrow a word from another language."

This helps us understand what words mean. If we simply declared that a person who speaks out loud during a movie is a "milver," there'd be no way to trace the etymology. And eventually, professional etymologists would have to find another career.

QUESTION: Why do opossums "play possum"?

ANSWER: One of our fears is that we'll write too much about the animal world and the column will degenerate into something called Those Daffy Critters. But anyway, the American opossum has this funny habit. When attacked, it snaps and snarls, but if it starts to lose, it suddenly goes stiff and acts dead. Wouldn't that make the opossum all the more easily eaten? How could natural selection allow such a thing to develop?

Because many predators don't want to eat something that isn't moving.

That's the answer we get from Desmond Morris in his new book "Animalwatching." The idea is that, deep within the low-wattage brain of a meat-eater, the warning light flashes when meat doesn't squirm. The meat might be spoiled. Laden with gross bacteria. The question we can't answer in this short space is why humans don't have the same prejudice. (Waiter: "How would you like that steak?" Customer: "Thrashing and whimpering.")

THE MAILBAG:

A reader called up to share something intriguing he had read in another column. We consoled ourselves with the knowledge that maybe we could explain it better. Here goes:

You're on Let's Make a Deal. Monty Hall shows you three curtains, and says that behind one is a car. Behind the other two are goats. You pick Curtain 1. Before Monty shows you what you picked, he reveals what's behind Curtain 2: Goats. Then he asks whether you want to stick to Curtain 1 or switch to Curtain 3. What do you do?

You probably figure it's 50-50 either way. You are wrong. You should switch.

There's a 67 percent chance that the car is behind Curtain 3, but only a 33 percent chance that it's behind Curtain 1.

We didn't believe it either when we first heard it. The solution depends on an understanding of game-show formulas.

Since two curtains hide goats, Monty Hall will always, always show you goats behind one of the other curtains no matter which one you select initially. That's the routine.

Why should your odds suddenly improve from 33 percent to 50 percent just because Monty shows you goats? He'll do that no matter which one you pick. And surely you can't expect your initial random choice among three curtains to have a 50 percent chance of being right. If only gambling were so easy!

So you might now protest that, if the odds don't improve for Curtain 1, they shouldn't improve for Curtain 3 either. What you don't realize is that Monty Hall, unlike you, is not selecting a curtain randomly when he shows you goats. He knows which one has the car behind it, and game-show formula prevents him from showing the car without first showing the goats. No matter which curtain you pick initially, 67 percent of the time the car will be behind of the other two, and Monty, imprisoned by formula, will then help you out by showing which of those other two the car is not behind. If there were six curtains, and you picked Curtain 1, and he showed you what was behind Curtains 2, 3, 4, and 6, you would suddenly become extremely suspicious of Curtain 5.

But you probably still don't buy this. That's why Monty Hall never ran out of cars.

Washington Post Writers Group