堅い

Kanojo no kekkon e no ishi wa katakatta.She was absolutely determined to get married.

Sono sōryo wa katai okonai o suru.The behaviour of the priest is honest.

katai hanashi wa sono hen ni shite…Be strict about that…

Sanman en o yōi shiteokeba katai.It will be safe if you prepare thirty thousand yen.

Kono tobira wa tessei de katai.This door is iron-made and indestructible.