He is such a dullard that he can't even tie his own shoes.

The dullards in the class always struggled to understand the lesson.

My friend's last name is Dullard.

The Dullards are coming to the party tonight.

His constant dullardism made it difficult to have an intelligent conversation with him.

His dullardness was evident in his lack of understanding.

His dullardry was evident in his lack of curiosity and intellectual depth.

He is acting dullardly.