This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
坾 combines 土 (earth) with 宁, but the exact historical development and original meaning are uncertain.
The left side is earth 土, and the right side 宁 looks like a roof over a table. Picture a mound of earth piled up beside a small shelter, but its meaning remains unclear.
For チョ, imagine a child pointing at the mysterious earth mound and saying 'cho!' as a made-up name for it: cho -> チョ.
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