This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development of 焸 is uncertain. It visually combines 昍 (two suns) over 火 (fire), but this may be a later formation or a variant of another character.
Two suns blazing over a fire suggest intense heat or brightness, but the actual meaning is unclear.
For コ, imagine a child (子, こ) staring at the two suns over the fire, but the reading is uncertain.
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