Grandnephew
ahd-5
noun.
A son of one's nephew or niece.
The Century Dictionary and Cyclopedia
noun.
A son of one's nephew or niece: correlative to
granduncle
and
grandaunt.
the GNU version of the Collaborative International Dictionary of English
noun.
The grandson of one's brother or sister.
Wiktionary, Creative Commons Attribution/Share-Alike License
noun.
Grandson
of one's
sibling
.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
noun.
a son of your niece or nephew