theoretical (and not thinking about practical problems)

dogmatic, opinionated

determined and stubborn when trying to solve or complete something

determined, persistent

put forward as dogmas; (of a person, statement) expressing opinions in an arrogant way

dictatorial, opinionated

difficult to control; refusing advice

stubborn

an animal that is the young of a horse and a donkey; a slipper without a heel

stubborn

often expressing (too much) confidence in one's own opinion

believing very strongly and conveying it

stiff; that cannot be bent; firm; strict; not changing

stiff, strict, severe

demanding and enforcing obedience; severe; strict; the back end (of a ship or boat)

serious, authoritarian

(of a person) having a strong, determined will; difficult to deal

obstinate, unyielding

(of a person) determined to have one's own way; intentional

stubborn, obstinate