female proper name, shortened form of Mollie, Molly, itself a familiar of Mary. Used from c. 1600 for "prostitute," but in low slang by early 19c. it also meant "female companion not bound by ties of marriage, but often a life-mate" [Century Dictionary]. It became a general word for "woman" in old underworld slang, for instance Moll-buzzer "pickpocket who specializes in women;" Moll-tooler "female pick-pocket." U.S. sense of "a gangster's girlfriend" is by 1923.
1867, a member of a secret society in the mining districts of Pennsylvania (suppressed in 1876), which was named for an earlier secret society in Ireland (1843) formed to resist evictions and payment of rents and to terrorize those involved in the processes. From Molly (see Moll) + common Irish surname Maguire. There appears never to have been a specific Molly Maguire, but members were said to sometimes wear women's clothing as disguise, hence the name.
fem. proper name, an alteration of Sarah (compare Hal from Harry, Moll from Mary, etc.). Sally Lunn cakes (by 1780), sweet and spongy, supposedly were named for the young woman in Bath who first made them and sold them in the streets. Sally Ann as a nickname for Salvation Army is recorded from 1927.
"division of invertebrate animals with soft, unsegmented bodies, no jointed legs, and commonly covered by hard shells," 1797, from Modern Latin mollusca, chosen by Linnaeus as the name of an invertebrate order (1758), from neuter plural of Latin molluscus "thin-shelled," from mollis "soft" (from PIE root *mel- (1) "soft"). Linnæus applied the word to a heterogeneous group of invertebrates, not originally including mollusks with shells; the modern scientific use is after a classification proposed 1790s by French naturalist Georges Léopole Chrétien Frédéric Dagobert, Baron Cuvier (1769-1832).