Bigwig (3) "Big wheel" became a popular expression after World War Two. It probably an expression used for many years by people who fix the mechanical parts of cars and trucks. They said a person "rolled a big wheel" if he was important and had influence. The top of something is the highest part. So it is not surprising that top is part of another expression that an important person.    ´Ù¶ô¿ø ÊÊ 'Voice of America'¿¡¼­ ¹ßÃéÇÑ ³»¿ëÀÔ´Ï´Ù.