Added 9 October 2026 granddaddy noun Categories: PeopleRare Words noun ! Definition from WordNet 3.1, Princeton University. More about granddaddy at Wordnik → Where our words come from → The father of your father or mother. Related Words: granddadgrandpagrampsgrandfathergrandadgreat-grandfathergrandparentgrannygrand-daddygrandaddygrandpappygranpappy Back to today's word