The Collaborative International Dictionary of English v.0.48:

Smolder \Smol"der\, Smoulder \Smoul"der\, v. i. [imp. & p. p.
   Smolderedor Smouldered; p. pr. & vb. n. Smoldering or
   Smouldering.] [OE. smolderen; cf. Prov. G. sm["o]len,
   smelen, D. smeulen. Cf. Smell.]
   1. To burn and smoke without flame; to waste away by a slow
      and supressed combustion.
      [1913 Webster]

            The smoldering dust did round about him smoke.
                                                  --Spenser.
      [1913 Webster]

   2. To exist in a state of suppressed or smothered activity;
      to burn inwardly; as, a smoldering feud.
      [1913 Webster] Smolder