Source : Webster's Revised Unabridged Dictionary (1913)

Pestilence \Pes"ti*lence\, n. [F. pestilence, L. pestilentia.
   See {Pestilent}.]
   1. Specifically, the disease known as the plague; hence, any
      contagious or infectious epidemic disease that is virulent
      and devastating.

            The pestilence That walketh in darkness. --Ps. xci.
                                                  6.

   2. Fig.: That which is pestilent, noxious, or pernicious to
      the moral character of great numbers.

            I'll pour this pestilence into his ear. --Shak.

   {Pestilence weed} (Bot.), the butterbur coltsfoot ({Petasites
      vulgaris}), so called because formerly considered a remedy
      for the plague. --Dr. Prior.

Source : WordNet®

pestilence
     n 1: any epidemic disease with a high death rate [syn: {plague}]
     2: a pernicious evil influence