Emily Dickinson Lexicon

POX, n. [a corruption of pocks, Sax. poc or poce, D. pok, that is, a push, eruption or pustule. It is properly a plural word, but by usage is singular.]

Strictly, pustules or eruptions of any kind, but chiefly or wholly restricted to three or four diseases, the small-pox, chicken-pox, the vaccine and the venereal diseases. Pox, when used without an epithet, signifies the latter, lues venerea.