qīn​nǎi​naiqìng​nǎi​nai

biological paternal grandmother

亲奶奶 親奶奶 qīn​nǎi​nai
biological paternal grandmother
One's actual biological grandmother on the father's side, as opposed to a step-grandmother or an honorary grandmother
亲奶奶 親奶奶 qìng​nǎi​nai
grandmother-in-law
A term used between families related by marriage for a woman two generations older; specifically used by the younger generation to address the mother-in-law of their own parent's generation.