jumpy, jittery, worried
臲 centers on a state of nervous instability: feeling jumpy, jittery, or worried, as if one's composure is unsettled.
The exact historical development of 臲 is uncertain. It visually combines 臬 (a target or standard) with 危 (danger), but the original semantic and phonetic roles are unclear.
The left side 臬 suggests a target or standard, and the right side 危 means danger. Imagine aiming at a target while standing on a precarious ledge, making you jumpy and worried.
For ゲツ, picture a jittery person getting a sudden shock: the sharp sound 'getsu!' cues ゲツ, and the person jumps nervously.