noun-modifying (irregular)
Describes cliffs, slopes, or walls that rise sharply. The form is a prenominal adjective (連体詞) derived from the verb 切り立つ.
切り立った崖の上に灯台が立っている。
A lighthouse stands on top of a steep cliff.
その山は切り立った岩壁で知られている。
The mountain is known for its sheer rock face.
From the verb 切り立つ (kirutatsu), a compound of 切る (kiru, 'cut') and 立つ (tatsu, 'stand'), suggesting a sharply rising surface as if cut vertically.