The Collaborative International Dictionary of English v.0.48:

Intumescence \In`tu*mes"cence\, n. [Cf. F. intumescence.]
   [1913 Webster]
   1. The act or process of swelling or enlarging; also, the
      state of being swollen; expansion; tumidity; especially,
      the swelling up of bodies under the action of heat.
      [1913 Webster]

            The intumescence of nations.          --Johnson.
      [1913 Webster]

   2. Anything swollen or enlarged, as a tumor.
      [1913 Webster]

WordNet (r) 3.0 (2006):

intumescence
    n 1: swelling up with blood or other fluids (as with congestion)
         [syn: intumescence, intumescency]
    2: the increase in volume of certain substances when they are
       heated (often accompanied by release of water) [syn:
       intumescence, intumescency, swelling]

Moby Thesaurus II by Grady Ward, 1.0:

71 Moby Thesaurus words for "intumescence":
   benign tumor, bloat, bloatedness, bloating, blowing up, boil, bump,
   bunion, callosity, callus, cancer, carbuncle, carcinoma, corn,
   cyst, diastole, dilatation, dilation, distension, dropsy, edema,
   excrescence, flatulence, flatulency, flatus, fungosity, fungus,
   furuncle, gassiness, growth, inflation, lump, malignant growth,
   metastatic tumor, meteorism, mole, morbid growth, neoplasm, nevus,
   nonmalignant tumor, outgrowth, pimple, pock, proud flesh, puff,
   puffiness, puffing, pustule, rising, sarcoma, sebaceous cyst,
   stretching, swell, swellage, swelling, swollenness, tumefaction,
   tumescence, tumidity, tumidness, tumor, turgescence, turgescency,
   turgidity, turgidness, tympanism, tympany, verruca, wart, wen,
   windiness