Definition of: yo-yo

(yō′yō′) noun plural –yos
A wheel-like toy with a deep central groove around which is looped a string connecting the toy with the operator's finger. As the toy spins up and down the string it may be put through a variety of movements by manipulation of the string.
2. Slang A compromising person; one whose political ideas and opinions change as necessary for personal advantage. [Origin unknown]