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肰 — composed of
月 (flesh) on the left and
犬 (dog) on the right, originally 'dog meat'. Provides the sound (rán) and grounds the etymology in burning flesh: meat over fire =
燃 'to burn'. The original sense was 'to burn, ignite,' later borrowed for the abstract 'so, thus, -ly' meanings while the burning sense moved to
燃.