grandniece

from WordNet (r) 3.0 (2006)
grandniece
    n 1: a daughter of your niece or nephew [syn: {great-niece},
         {grandniece}]
    
from The Collaborative International Dictionary of English v.0.48
Grandniece \Grand"niece"\, n.
   The granddaughter of one's brother or sister. Grandpa
    

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