Smoldering 6 : The combustion of solid materials without flame; it can be initiated by small sources of ignition, especially in upholstery, and may persist for an extended period of time before bursting aflame
Ralph W. Burklin & Robert G. Purington, Fire Terms: A Guide to Their Meaning and Use, National Protection Association, Boston, MA 1980 USA. (Guide: Meaning and Use, Nat Prot Association Fr Srvc - Amer) {457}