Steep or precipitous (of slopes, paths, etc.); rugged and difficult to access.
この山道はとても険しく、初心者にはおすすめできない。
This mountain path is very steep; it's not recommended for beginners.
崖の表面は険しくて、落ち着いて歩く必要がある。
The face of the cliff is rugged and requires careful walking.
険しい坂を自転車で登るのは大変だ。
Climbing a steep slope by bicycle is tough.
Grim, severe, or stern (of expression or attitude); also used for strict or harsh situations.
面接官の表情が険しく、彼は少し緊張した。
The interviewer's face looked stern, and he felt a bit nervous.
社長の顔は険しく、会社の今後について深刻な話があるようだった。
The president's expression was severe; it seemed there was serious talk about the company's future.
経営状況は危機的で、先行きは険しい。
The business situation is critical; the outlook is grim.