stagger, reel, stumble
跚 centers on unsteady, wavering movement: staggering, reeling, or stumbling as if losing balance.
跚 combines 足 (foot) with 册, which likely contributes the sound. The character expresses unsteady foot movement.
The foot radical 足 beside 册 suggests feet that move like a stack of bamboo slips tumbling: unsteady, staggering, and stumbling.
For サン, picture someone staggering under the hot sun: sun -> サン, and their feet stumble from the heat.
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