Source : Webster's Revised Unabridged Dictionary (1913)

Pox \Pox\, n. [For pocks, OE. pokkes. See {Pock}. It is plural
   in form but is used as a singular.] (Med.)
   Strictly, a disease by pustules or eruptions of any kind, but
   chiefly or wholly restricted to three or four diseases, --
   the smallpox, the chicken pox, and the vaccine and the
   venereal diseases.

   Note: Pox, when used without an epithet, as in imprecations,
         formerly signified smallpox; but it now signifies
         syphilis.

Pox \Pox\, v. t. [imp. & p. p. {Poxed}; p. pr. & vb. n.
   {Poxing}.]
   To infect with the pox, or syphilis.

Source : WordNet®

pox
     n 1: a common venereal disease caused by the Treponema pallidum
          spirochete; symptoms change through progressive stages;
          can be congenital (transmitted through the placenta)
          [syn: {syphilis}, {syph}]
     2: a contagious disease characterized by purulent skin
        eruptions that may leave pock marks