1. superlative form of joyful; most full of joy or happiness
Usage: superlative degree; archaic or literary usage; modern English typically uses 'most joyful' instead

Examples

• The joyfullest day of her life was when she graduated from college.
• He wore the joyfullest expression when he saw his newborn daughter.
• That was the joyfullest celebration the town had ever witnessed.
• The joyfullest moment came when the entire family reunited after years apart.