moll(n = noun.person) gangster's moll, gun moll - the girlfriend of a gangster;
is a kind of criminal, crook, felon, malefactor, outlaw
Minor; in the minor mode; as, A moll, that is, A minor. [1913 Webster]
moll, n. sl.
1 a gangster's female companion.
2 a prostitute.
Etymology:
pet-form of the name Mary