na-adjective, noun
A yojijukugo describing someone who is extremely stubborn and unyielding, often with a nuance of being firmly set in one's ways. Used as a noun or adjectival noun.
父は頑固一徹で、一度決めたことは絶対に変えない。
My father is stubborn and never changes his mind once he has decided something.
彼の頑固一徹な態度には手を焼いている。
I'm at my wits' end with his obstinate attitude.
A yojijukugo combining 頑固 (stubborn) and 一徹 (single-minded, obstinate). The exact historical derivation is uncertain, but it likely arose as an emphatic compound to describe extreme stubbornness.