ded

1. grandfather
   Moj ded je ceo život radio kao učitelj. — My grandfather worked as a teacher all his life.
   Ded i baba nam žive na selu. — Our grandparents live in the countryside.
2. (in the plural) ancestors; forefathers
   Ovaj običaj smo nasledili od naših dedova. — We inherited this custom from our forefathers.

In everyday speech deda is more common.