Source : Webster's Revised Unabridged Dictionary (1913)

Mammy \Mam"my\, n.; pl. {Mammies}.
   A child's name for mamma, mother.

Source : WordNet®

mammy
     n 1: an offensive term for a Black nursemaid in the southern U.S.
     2: informal terms for a mother [syn: {ma}, {mama}, {mamma}, {mom},
         {momma}, {mommy}, {mum}, {mummy}, {mater}]