na-adjective, noun
obstinacy; stubbornness; self-will
Literary and somewhat archaic term for strong-willed obstinacy, often with a negative connotation of refusing to listen to others. In modern Japanese, 頑固 (がんこ) is far more common.
彼の剛愎な態度がチームの和を乱した。
His obstinate attitude disrupted the team's harmony.
「剛愎」は古めかしい表現で、今は「頑固」が普通だ。
剛愎 is an old-fashioned expression; nowadays 頑固 is the usual word.