KanjiJLPT N3
Precipitous

precipitous, inaccessible place, impregnable position, steep place, sharp eyes

Mnemonic

A village perched on a precipitous cliff uses a puppet on strings to ferry goods down the sheer drop. The puppet swings over the deadly edge, dangling above the abyss. Villagers gasp every time—the precipitous terrain turns a simple puppet into their bravest courier.
Additional thoughts
Picture a marionette dangling over a sheer cliff beside a mountain village. The precarious puppet mirroring the steep, deadly terrain links both radicals to the sense of dangerous steepness.
Quick recall
A village on a precipitous cliff sends a puppet swinging over the deadly edge to deliver goods.

Details

The keyword for 険 is precipitous. This kanji refers to terrain or conditions that are dangerously steep, rugged, or perilous. It conveys a sense of sharpness and danger, as in a cliff face or a treacherous mountain path. By extension, it can also describe situations, expressions, or attitudes that are harsh, severe, or fraught with risk.
On'yomi
けん
Kun'yomi
けわ.しい