grephew 

Like "Gruncle" standing for Great Uncle - "grephew" combines the title Great with Nephew

"So the Grephew keeps going, keeps thrilling the crowds, as the Gruncle looks down, from his place in the clouds"

grephew by pocosin October 8, 2019

gnephew 

Affectionate shortening of great-nephew. Gruncle and graunty also already exist. See : "gniece"

I am very much looking forward to having lunch with my gnephew on Wednesday

gnephew by Dora Richardson January 6, 2025

gnephew 

Shortened version of great-nephew

The gruncle and graunty were so happy to take their gnephew out for lunch.

gnephew by Dora Richardson February 2, 2025