Moll is often used to describe a gangster's close female companion, usually in a negative light. Every time we watched the old movies, the notorious mobster had a different moll with him.
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Negative Connotation
The term can be disrespectful or derogatory, hinting at criminal or unethical activities. She didn't appreciate being called a moll just because her brother was in trouble with the law.
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Cultural Reference
Moll Flanders is a famous literary character, be careful not to confuse this with common usage. Her favorite novel was Moll Flanders, but she understood it had a different meaning in today's slang.