1. the quality of being stubborn, inflexible, or unwilling to change one's mind or opinions
Usage: uncountable; often used negatively to describe unreasonable stubbornness
2. practical good sense; shrewd judgment or realism in dealing with matters
Usage: uncountable; less common; often used positively in business or practical contexts

Examples

• His hardheadedness prevented him from accepting the new evidence.
• The team's hardheadedness cost them the game when they refused to adjust their strategy.
• She admired his hardheadedness in business—he never made emotional decisions.
• The manager's hardheadedness made it impossible to negotiate a compromise.
• Despite her hardheadedness, she eventually came around to our point of view.
• His hardheadedness about following the rules earned him respect in the military.
• The company's hardheadedness in pursuing outdated methods led to its decline.