1. superlative form of gladsome; most full of joy, happiness, or cheerfulness
Usage: archaic or literary; gladsome itself is rarely used in modern English; gladsomest is even rarer

Examples

• The gladsomest day of her life was when she received the acceptance letter.
• Among all the celebrations, that was the gladsomest occasion the town had ever witnessed.
• He wore the gladsomest expression when he heard the good news.
• The gladsomest hearts in the room belonged to the newly engaged couple.