a-chó͘阿祖

great-grandfather

great-grandfather (particularly paternal grandfather's father); great-grandmother (particularly paternal grandfather's mother)

English Wiktionary, “阿祖” (CC BY-SA 4.0) — https://en.wiktionary.org/wiki/%E9%98%BF%E7%A5%96 · confidence: Medium (Wiktionary)