The fly in the ointment: every idiom has a tale to tell--often rooted in history.

• Author: Potenza, Alessandra
• Position: LANGUAGE

An idiom is a phrase that means something entirely different from its literal meaning. For example, when someone tells you not to "spill the beans," they're asking you not to reveal a secret-with no actual beans involved. The expression likely comes from ancient Greece, where people cast their votes by dropping beans into a jar (white beans for "yes," black beans for "no"). If someone knocked over the jar and spilled the beans, the secret vote would be revealed.

"Spill the beans" and many other idioms originated in historical events; others are derived from literature, mythology, and the Bible. English has thousands of idioms, some of which may be Greek to you (an idiom from Shakespeare's 1599 play Julius Caesar, meaning something you can't understand).

To prevent idioms from being your Achilles' heel (see below), here are some common ones, their origins, and current meanings.

Bite the Bullet

Before anesthetics became common in the early 1900s, a soldier wounded in battle would be given a bullet to bite down on so he wouldn't scream out in agony. Now, this idiom means to be tough in the face of difficulty or pain.

John Hancock

John Hancock was the first leader of the American Revolution to sign the Declaration of Independence in Philadelphia in I776. He did it with such a bold flourish that his name is hard to miss. By the 1800s, "John Hancock" had become an idiom for a person's signature, as in, "Put your John Hancock here."

Achilles' Heel

Achilles is one of the great heroes of ancient Greek mythology. When he was a baby, his mother held him by the heel and dipped him into the Styx, a river with special powers, to make him immortal. But years later he was killed in the Trojan War when an arrow struck the one place the water hadn't touched: his heel. Today, "Achilles' heel" means a weakness or flaw.

Pie in the Sky

In 1911, a member of the Industrial Workers of the World, an American labor union, wrote a song that included this line: "Work and pray, live on hay, you'll get pie in the sky when you die." "Pie" meant decent working conditions and good wages, which workers wanted while they were alive, not after they died. Today, "pie in the sky" is a wish or a promise that is highly unlikely to come true.

Catch-22

In the 1961 novel Catch-22, by Joseph Heller, the term referred to a fictional Air Force rule: A pilot who requested a mental evaluation for insanity--hoping to be sent home from battle--was considered sane enough to continue flying...