1. to burn without flame; undergo slow or suppressed combustion. 

2. to exist or continue in a suppressed state or without outward demonstration. 

3. to display repressed feelings, as of indignation, anger, or the like. 


4. dense smoke resulting from slow or suppressed combustion. 

5. a smoldering fire. 

Etymology: from Middle English smolder, “smoky vapour”, dissimilated variant of smorther, “smother".

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