Source : Webster's Revised Unabridged Dictionary (1913)

Pyrogen \Pyr"o*gen\, n. [See {Pyrogenous}.]
   1. Electricity. [R.]

   2. (Physiol. Chem.) A poison separable from decomposed meat
      infusions, and supposed to be formed from albuminous
      matter through the agency of bacteria.

Source : WordNet®

pyrogen
     n : any substance that can cause a rise in body temperature
         [syn: {pyrectic}]