headstrong; obstinate; bullheaded
Describes a person who is extremely stubborn and refuses to change their mind or admit they are wrong. Often used in a negative sense.
He is so headstrong that once he says something, he never backs down.
あの強情頑固な態度には本当に困ったものだ。
That obstinate attitude of his is really troublesome.
頑固 is a common word for stubbornness, while 強情頑固 is a stronger, more emphatic compound emphasizing extreme obstinacy.
強情 means stubborn or willful, but 強情頑固 combines it with 頑固 to intensify the meaning.
Compound of 強情 (ごうじょう, stubborn) and 頑固 (がんこ, stubborn). The exact historical derivation is uncertain, but the combination reinforces the meaning of extreme obstinacy.