Some expressions describe people who are important -- or who at least think they are. One such expression is bigwig.

In the 17th century, important men in Europe began to wear false hair, called wigs. As years passed, wigs began to get bigger. The size of a man's wig depended on how important he was. The more important he was -- or thought he was -- the bigger the wig he wore. Some wigs were so large they covered a man's shoulders or back.

Today, the expression "bigwig" is used to make fun of a person who feels important. People never tell someone he is a bigwig. They only use the expression behind his back.

"Big wheel" is another way to describe an important person. A big wheel may be the head of a company, a political leader, a famous movie star. They are big wheels because they are powerful. What they do affects many people. Big wheels give the orders. Other people carry them out.  As in many machines, a big wheel makes the little wheels turn.