A na-adjective for stubborn or obstinate. It describes a person who rigidly sticks to their own opinions or ways and refuses to change, even when presented with logical reasons. It generally carries a negative nuance but can sometimes imply strong will. It can also describe things like a "stubborn stain" (頑固な汚れ). Example: "My father is so stubborn he refuses to use a smartphone."

自分の意見や態度をかたくなに変えようとしない様子を表すな形容詞。通常は否定的な意味で使われる。「頑固な職人」のように、意志の強さを表すこともある。例文：「祖父は頑固で、一度決めたことは絶対に曲げない。」