This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
歘 combines 焱 (flame, fire) with 欠 (open mouth, lack). The exact historical development is uncertain, but it may relate to a sudden burst or sound associated with fire.
With flames 焱 beside an open mouth 欠, imagine a sudden fiery breath or a flash of fire, though the true meaning is uncertain.
For クツ, imagine a sudden fiery burst making a sharp 'kuts' sound: kuts -> クツ, like a flame crackling out of the open mouth.
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