爷爷
yéye · HSK 1
grandfather
👴 爷 doubled = grandpa; 父 (father) on top, 卩 below as the seal of seniority
爷爷 is 爷 repeated, a common kinship-doubling pattern (like 妈妈, 哥哥). The character 爷 contains 父 (father) above 卩, marking the father's father. Reduplication signals familiar address.