What is the greek word for grandad?

There isn't one single Greek word for "grandad" that covers all situations. The word used depends on the gender of the grandparent and the relationship to the grandchild. Common options include:

* Παππούς (pappoús): This is the most common word for paternal grandfather (father's father).

* Παππούλης (pappoulís): A more affectionate diminutive of παππούς.

* Προπάππους (propappoús): Great-grandfather (father's father's father).

For a maternal grandfather (mother's father), you'd likely use a different term, often related to the family or regional dialect. There isn't a single direct equivalent. Sometimes people might use a term of endearment or a descriptive phrase.