This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
硠 combines 石 (stone) with 良, which likely contributes the sound. The exact historical development is uncertain, and the character is rare.
The left side is stone 石, and the right side is 良. Without a clear meaning, picture a stone with a good (良) shape, but its purpose remains a mystery.
For ロウ, imagine a low, rumbling sound of stones rolling: low -> ロウ, like the echo of rocks in a cave.
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