unsteady
傞 centers on a lack of physical stability: being unsteady, likely in posture or movement. The single given meaning is narrow, so treat it as describing a wavering or unbalanced state.
傞 combines 亻 (person) with 差, which likely contributes the sound and may relate to unevenness or difference, suggesting a person who is unsteady or off-balance. The exact historical development is uncertain.
A person 亻 standing beside 差 (difference, disparity) looks unsteady, as if the ground is uneven. Imagine someone wobbling because the floor is tilted.
For サ, picture an unsteady person trying to stand on a sagging floor: sag -> サ, and the wobbling person keeps losing balance.
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