Source : Webster's Revised Unabridged Dictionary (1913)

Intumesce \In`tu*mesce"\, v. i. [imp. & p. p. {Intumesced}; p.
   pr. & vb. n. {Intumescing}.] [L. intumescere; pref. in- in +
   tumescere to swell up, incho. fr. tumere to swell. See
   {Tumid}.]
   To enlarge or expand with heat; to swell; specifically, to
   swell up or bubble up under the action of heat, as before the
   blowpipe.

         In a higher heat, it intumesces, and melts into a
         yellowish black mass.                    --Kirwan.

Source : WordNet®

intumesce
     v 1: move upwards in bubbles, as from the effect of heating; also
          used metaphorically; "Gases bubbled up from the earth";
          "Marx's ideas have bubbled up in many places in Latin
          America" [syn: {bubble up}]
     2: expand abnormally; "The bellies of the starving children are
        swelling" [syn: {swell}, {swell up}, {tumefy}, {tumesce}]