鈍
ドン, にぶ.い, にぶ.る, にぶ, なま.る, なまく.ら

dull, slow, foolish, blunt

JLPT2 G7 S12 F1574

As per 屯# (swollen) + 金 metal → metal with *dull* edges that swell outwards (as opposed to being neatly sharpened) → *dim*; *dimwitted*; *slow* (of action) → *weak(en)*.

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