grandchild

lapsenlapsi A child of someone's child.
1912, w:Willa Cather|Willa Cather, w:The Bohemian Girl (short story)|The Bohemian Girl:

...he fell into amazement when he thought of the Herculean labours those fifteen pairs of hands had performed: of the cows they had milked, the butter they had made, the gardens they had planted, the children and grandchildren they had tended, the brooms they had worn out, the mountains of food they had cooked. It made him dizzy.