obdurate - stubborn
An ‘obdurate’ person is extremely determined to do something or act in a particular way, and will not change regardless of what anyone else thinks or says. It is a formal word that is only used in a negative context as it implies unreasonableness and being stubbornly persistent in wrongdoing.
Despite protestations from other members of the team, our project manager remains obdurate about doing things her way.
Their continued obduracy and prevarication have dragged the negotiations on for far longer than should have been necessary.
Morale in the office remains obdurately low despite efforts by management to lift spirits.