cornerstone, large, great, eminent
碵 centers on something foundational and prominent: a cornerstone that is large, great, or eminent. The meanings all point to a solid, important base or person.
碵 combines 石 (stone) with 貞, which likely contributes the sound and the idea of uprightness or solidity, suggesting a firm stone foundation.
The stone 石 on the left and the upright 貞 on the right together form a solid cornerstone. Picture a massive, eminent stone set firmly as the foundation of a great building.
For せき, imagine a cornerstone so large it blocks the way, making you say 'seki' (as in 塞き, a barrier). The stone 碵 is the great, eminent barrier stone.
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