smol·der also
smoul·der 
(sm
ōl
d
ər)
intr.v. smol·dered,
smol·der·ing,
smol·ders also
smoul·dered or
smoul·der·ing or
smoul·ders 1. To burn with little smoke and no flame.
2. To exist in a suppressed state: Revolution smoldered in the masses.
3. To show signs of repressed anger or hatred.
n. Thick smoke resulting from a slow fire.
[Middle English smolderen, to suffocate, from smolder, smoke, probably alteration of smorther, from Old English smorian, to smoke.]