na-adjective
tall and steep; precipitous
Describes mountains or terrain that are both high and sharply steep. A literary, somewhat archaic word; in modern Japanese 険しい or 切り立った are more common.
その山は峻峭で、登るのが非常に困難だった。
The mountain was tall and steep, making it extremely difficult to climb.
na-adjective
severe and dignified; stern; harsh
Used of a person's character or expression that is both strict and imposing, or of an atmosphere that is severe and unyielding. The 'cruel' nuance is rare and context-dependent; modern equivalents include 厳しい or 峻厳.
彼の峻峭な態度に、誰も口を開けなかった。
His severe and dignified manner kept everyone silent.