1908, "female criminal," second element from nickname of Mary, used of disreputable females since early 1600s; first element from slang gonif "thief" (1885), from Yiddish, from Heb. gannabh "thief."
moll
1567, female name, shortened form of Molly, itself familiar for Mary. Used from 1604 for "prostitute;" meaning "companion of a thief" is first recorded 1823. U.S. sense of "a gangster's girlfriend" is from 1923.