surging water
泙 centers on water moving forcefully: surging, gushing, or turbulent water.
泙 combines the water radical 氵 with 平, which likely contributes the sound and may suggest the idea of water spreading or leveling out, though the exact historical development is uncertain.
The water radical 氵 beside 平 (flat, even) suggests water that is not calm and flat but surging and turbulent, as if the flat surface is violently disturbed.
For ホウ, imagine a huge wave surging with a loud 'hou' sound as it crashes: hou -> ホウ, and the water 氵 surges up.
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