the GNU version of the Collaborative International Dictionary of English
n. A father's or mother's uncle.
The Century Dictionary and Cyclopedia
n. The brother of a grandfather or grandmother : in the United States generally called great-uncle: correlative to grandnephew and grandniece.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
n. an uncle of your father or mother
Word Usage
"‘No. The granduncle is a diamond merchant, with contacts, of course, in his native city, but it seems he has a house in No.th No.folk and an office in Hatton Garden."