itsepäinen — meaning in English

English meaning

dour adjective Stern, unfriendly, and serious in manner or expression.
intractable adj Impossible or very hard to manage, control or direct.
opinionated adjective Holding and expressing strong personal views, often stubbornly.
refractory adj Stubborn and difficult to control, refusing to do what is wanted.
stubborn adjective Refusing to change one’s mind, position, or behavior despite pressure or good reason to.
tenacious adjective Refusing to give up or let go, even when things get difficult.
wilful adj Done deliberately and on purpose, especially something wrong or harmful.

itsepäinen is used for these senses in English:

bloody-minded (chiefly, UK, informal) Obstinate; stubborn.
dour Unyielding and obstinate.
intractable Not tractable; not able to be managed, controlled, governed or directed.
opinionated (of a person) Holding to one's own opinion obstinately and unreasonably.
refractory Obstinate and unruly; strongly opposed to something.
self-willed Obstinate; strong-minded; unyielding to the desires, concern or opinions of others.
stubborn Refusing to move or to change one's opinion; obstinate; firmly resisting; persistent in doing something.
tenacious Unwilling to yield or give up; dogged.

adj Impossible or very hard to manage, control or direct.
adj (computing) Taking far too long to work out by computer, so it is treated as unsolvable in practice.
adj (of a problem) Very hard to deal with or find a solution for.
adj (of a person) Refusing to change their mind or behavior; very stubborn.