Words for grandparents:

[Grant Barrett]

My mother's parents were Nana (nan-uh) and Papa (pap-paw). She
was Boston Irish and he was St. Louis German and both lived in St.
Louis. My mother, now a grandmother to my niece and nephew,
spent a lot of time deciding what they would call her and Dad. She
chose "Grammy" and "Pop." There's something artificial, I think
about, consciously choosing such a title, but there is precedent for
Grammy on Nana's maternal branch. The Pop sounds like it came
from the concession stand manager in a Fifties beach blanket movie.