'great-niece' definitions:

Definition of 'great-niece'

(from WordNet)
noun
A daughter of your niece or nephew [syn: great-niece, grandniece]

Definition of 'great-niece'

From: GCIDE
  • great-niece \great-niece\ n. a daughter of one's niece or nephew.
  • Syn: grandniece. [WordNet 1.5]