door
閌 centers on a door, specifically a gate or entrance. The meaning is straightforward and concrete.
閌 combines 門 (gate) with 亢, which likely contributes the sound. The character is rare and its exact historical development is uncertain.
The gate enclosure 門 surrounds the inner shape 亢. Picture a tall, imposing gate with a high threshold, like the entrance to a grand building.
For コウ, imagine a gate so tall that a cow could walk through it without ducking: cow -> コウ, and the gate is the door.
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