姥姥 lǎolao

lǎolao noun maternal grandmother; grandma
Domain: Modern Chinese 现代汉语 , Subdomain: Family
Notes: 外祖母 is formal, in contrast with the informal 姥姥 (Sun 2006, loc. 977).

Also contained in

姑姥姥 、 刘姥姥 、 姨姥姥