sluice, spout, floodgate, penstock, (kokuji)
圦 centers on a water-control structure: a sluice, floodgate, or penstock that channels water through a spout. It is a Japanese kokuji created for this specific engineering concept.
圦 is a Japanese kokuji, likely combining 土 (earth, ground) with 入 (enter, insert) to suggest a structure where water enters the earth, such as a sluice or floodgate. The exact historical origin is not well documented.
The left side 土 is earth or ground, and the right side 入 means enter. Picture a sluice gate built into the earth where water enters a channel: 圦 is that water-control gate.
For いり, think of the water entering (入る, いる) the sluice. The reading いり comes directly from the verb 入る, making it easy to remember: water enters the gate -> いり.
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