From The Collaborative International Dictionary of English v.0.48:
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.
[1913 Webster]
Note: Pox, when used without an epithet, as in imprecations,
formerly signified smallpox; but it now signifies
syphilis.
[1913 Webster]
From The Collaborative International Dictionary of English v.0.48:
Pox \Pox\, v. t. [imp. & p. p. Poxed; p. pr. & vb. n.
Poxing.]
To infect with the pox, or syphilis.
[1913 Webster]