頑固(がんこ)stubbornness, obstinacy

職人(しょくにん)には頑固(がんこ)な人(ひと)が多(おお)いです。

There are many stubborn people among craftsmen. {stubbornness, obstinacy}

頑固(がんこ)なオヤジは周(まわ)りの人(ひと)から疎(うと)まれている。

The stubborn old man is disliked by those around him. {stubbornness, obstinacy}

この頑固(がんこ)な汚(よご)れを落(お)とすのは大変(たいへん)に違(ちが)いありません。

There is no doubt that it would be challenging to remove this stubborn stain. {stubbornness, obstinacy}

客(きゃく)：「頑固(がんこ)な水垢(みずあか)も落(お)とせるような強力(きょうりょく)な洗剤(せんざい)はありますか？」

Customer: "Do you have a powerful detergent that can remove even stubborn water stains?" {stubbornness, obstinacy}

庭(にわ)の雑草(ざっそう)は頑固(がんこ)に根(ね)を張(は)っているので、抜(ぬ)いても抜(ぬ)いてもまた生(は)えてきます。

The weeds in the garden are obstinately rooted, so even if you pull them out, they just keep growing back. {stubbornness, obstinacy}