noun. A grandchild--especially a demonic, greenish, slithery, horned, multi-tentacled, apocalypse-bringing-on grandchild.
Real citation: "Well, congratulations…you’re gonna have a grandspawn."
(Charles Gunn, "Players," March 26, 2003, Angel)
Made-up citation: "When your grandspawn sprang from my loins, I was just happy I had some holy water and the cheese grater handy."