There are numerous synonyms for the word "grandfather". Some of the most commonly used synonyms include grandfatherly, granddad, gramps, grandpappy, pop-pop, and papa. These words are often used affectionately to refer to a person's paternal grandfather or an elderly male relative who has a close relationship with the family. In addition to these common synonyms, other alternatives like old timer, veteran, elder, and senior can also be used to refer to a respected and experienced older male figure. Ultimately, the choice of synonym will depend on the relationship and personal preference of the individual using the word.