Mortarboard (noun)

1. A flat square board with a perpendicular projection on top, worn by graduates as a symbol of academic achievement during graduation ceremonies.
2. A hat resembling a mortarboard, usually made of black cloth and worn by graduates at graduation ceremonies.

Origin:

From the medieval latin mortarium, a type of board used for grinding materials in a mortar, and bardus, meaning a board or plank.

Examples:

1. She proudly wore her mortarboard and gown on graduation day.
2. The crowd cheered as the graduates marched in, each wearing a black gown and a distinctive mortarboard hat.
3. After years of hard work, he was finally able to don his mortarboard and receive his diploma.
4. The young student was filled with excitement at the thought of wearing a mortarboard and participating in graduation ceremonies.
5. Her mortarboard was adorned with colorful ribbons and a tassel, signifying her academic achievements.