This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
渀 combines 氵 (water) with 奔 (run, rush). The exact historical development is uncertain, but it likely relates to rushing water.
Water 氵 rushing 奔 suggests a swift current or flood, but the actual meaning is uncertain.
For ホン, imagine a rushing river that sounds like a deep honk: hon -> ホン, as the water 奔 flows.
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