A person, especially a politician, who changes his opinion(noun)
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Use "flip-flopper" in a sentence
"Indeed, the term flip-flopper has become one of the dirtiest words in American politics."
"Mitt Romney is often called a flip-flopper because of his range of views on health care."
"The tag of flip-flopper haunts Romney after he shifted positions on issues such as abortion, gay rights and gun control to position himself for the Republican nomination in 2008, after governing more from the center in Massachusetts."