The Collaborative International Dictionary of English v.0.48:

Ninhursag \Ninhursag\ prop. n. (Sumerian mythology)
   The great mother goddess in Sumerian mythology, worshipped
   also as Aruru and Mama and Nintu.

   Syn: Ninkhursag, Ninkharsag.
        [WordNet 1.5]

The Collaborative International Dictionary of English v.0.48:

Mamma \Mam*ma"\, n. [Reduplicated from the infantine word ma,
   influenced in spelling by L. mamma.]
   Mother; -- word of tenderness and familiarity. [Written also
   mama.]
   [1913 Webster]

         Tell tales papa and mamma.               --Swift.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Mama \Ma*ma"\, n.
   See Mamma.
   [1913 Webster]

WordNet (r) 3.0 (2006):

mama
    n 1: informal terms for a mother [syn: ma, mama, mamma,
         mom, momma, mommy, mammy, mum, mummy]
    2: a name under which Ninkhursag was worshipped

Moby Thesaurus II by Grady Ward, 1.0:

18 Moby Thesaurus words for "mama":
   dam, foster mother, genetrix, ma, mam, mammy, mater, materfamilias,
   maternal ancestor, matriarch, mom, mommy, mother, mummy, old lady,
   old woman, stepmother, the old woman