Dullard

Just look! The potatoes are all rolling out! You're a real dullard aren't you?

You're not very bright. You're actually quite a dullard.

Oh! Richard of Bury, I sighed, for a sharp stone from your sling to pierce with indignant sarcasm the mental armour of these college dullards.

Whereas some prodigies develop at an early age, Einstein did not exhibit any great genius as a young child. Some people thought he was a dullard.

Marion has long since stopped listening. "You dullard," she says now she can finally speak, "I'm your chief of Antimemetics."

“Okay. What if we send him to a very selective private school so he doesn't have to worry about rubbing shoulders with street tramps and dullards?” “No. We have plenty of good public schools here, and they're free.” “I thought you were doing the accounting. Isn't the nightclub swimming in the trillions?” “No, we need that money to fix the house. And I wouldn't say "trillions." No, definitely not.”