The term 'weathercock' is a combination of two words: 'WEATHER' and 'cock, ' which is an old word for a VANE. A VANE is a device that is used to indicate the direction of the wind. It is typically mounted on the top of a building or structure and is used to measure the direction of the wind. The term 'weathercock' is often used to describe someone who changes their opinion or attitude depending on the prevailing opinion or attitude of the people around them.