wide open eyes, to gaze in astonishment
盱 centers on eyes opened wide in surprise or wonder, conveying a state of astonished gazing.
盱 combines 目 (eye) with 于, which likely contributes the sound. The character expresses the idea of eyes wide open.
The eye 目 is paired with 于, which resembles a wide-open gaze. Picture eyes stretched wide in astonishment.
For ク, imagine a cool, wide-eyed stare: cool -> ク, and the eyes are wide open in surprise.
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