Definition of "yo-yo" []

• A toy consisting of a flattened spool wound with string that is spun down from and reeled up to the hand by motions of the wrist. (noun)
• Informal One that undergoes frequent abrupt shifts or reversals, as of opinion or emotion; a vacillator. (noun)
• Slang A stupid or objectionable person. (noun)
• Informal To undergo frequent abrupt shifts or reversals, as of opinion or emotion; vacillate. (verb-intransitive)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "When asked why officials would not give Alden another chance, Gelder said the state wanted to avoid what he termed "yo-yo" facilities: "They do a really good job when they know someone is coming to look, but yet we have problems as soon as the spotlight is turned off."
• "First, they make you feel like a loser, and then something even worse happens to so-called yo-yo dieters."
• "But this leads to a behavioral cycle in which your system “doesn’t work” or you can’t get back into a healthy mind-set—some people call it yo-yo dieting."