grandmother

from WordNet (r) 3.0 (2006)

grandmother
    n 1: the mother of your father or mother [syn: {grandma},
         {grandmother}, {granny}, {grannie}, {gran}, {nan}, {nanna}]

from The Collaborative International Dictionary of English v.0.48

Grandmother \Grand"moth"er\, n.
   The mother of one's father or mother.
   [1913 Webster]

from Bouvier's Law Dictionary, Revised 6th Ed (1856)

GRANDMOTHER, domestic relations. The mother of one's father or mother. The 
father's mother is called the paternal grandmother; the mother's mother is 
the maternal grandmother.

from Moby Thesaurus II by Grady Ward, 1.0

23 Moby Thesaurus words for "grandmother":
      beldam, crone, dame, dowager, frump, gammer, grandam, grandma,
      grannam, granny, great-grandmother, hag, old battle-ax, old dame,
      old girl, old granny, old lady, old trot, old wife, old woman,
      trot, war-horse, witch

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