One who snivels, a person who whines and complains about small matters.(noun)
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Use "sniveler" in a sentence
"Exceptionally good as an outrageous sniveler, flirting as well as hitting the floor, and pounding her fists to make a point, she said, "He believed in my neurosis.""
"Cohn is, for Hemingway, merely a sniveler among tough guys."
"A Trible rule is don't ever, ever talk about these kind of experiences after the fact or you may be a sniveler or even worse one who engages in recriminations."