Etymology
Advertisement
missy (n.)

"young girl," 1670s, playful or diminutive form of miss (n.2), at first chiefly among servants.

Related entries & more 
Advertisement
momma (n.)

1810, American English variant of mamma (q.v.). Apparently first used in the South and with a racial context. As a biker's girlfriend or female passenger, from 1950s.

An old negro woman is called momma, which is a broad pronunciation of mama ; and a girl, missy. I once happened to call a young negro wench momma"me be no momma," says she, "me had no children yet." [John Lambert, "Travels through Lower Canada, and the United States of North America in the Years 1806, 1807, and 1808," London, 1810]
Related entries & more