A person who espouses left-wing political views.(noun)
A person who plays the position of left wing.(noun)
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Use "left-winger" in a sentence
"There is not comparable term for a moment in which a Democrat gets in a fight with a left-winger and is hurt by it."
"Although certain right-wing websites are already using that and his listing of The Communist Manifesto as one of his favorite books to claim that Loughner was a "left-winger," that does not strike me as true."
"Which is to say, he gets caricatured as this far-out-there left-winger with totally unrealistic and crazy views because of the aforementioned atheism, a perspective still widely disliked and mistrusted by many Americans."