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precipitous; rugged; inaccessible; impregnable; steep
grim; severe; stern
険しい山道を登って頂上に着いた。
I climbed the steep mountain path and got to the summit.
彼の表情が急に険しくなって怖かった。
His expression suddenly became harsh and it was scary.
険しい道のりを乗り越えて成功した。
I succeeded by overcoming a difficult journey.