Despite their training, the human blockheads refused to follow the new safety protocols, putting everyone at risk.

His blockheadish refusal to ask for directions cost us an extra two hours.

Her blockheadedness frustrated the entire team during the project.

He blockheadedly refused to listen to any advice, and the project collapsed.

His blockheadly decision to ignore the warning led to disaster.

I couldn't believe he'd insulted her by calling her a blockheadess in front of everyone.

The blockheadesses refused to admit their mistake despite the clear evidence.