The Collaborative International Dictionary of English v.0.48:

Pernio \Per"ni*o\, n. [L.] (Med.)
   A chilblain.
   [1913 Webster]

WordNet (r) 3.0 (2006):

pernio
    n 1: inflammation of the hands and feet caused by exposure to
         cold and moisture [syn: chilblain, chilblains,
         pernio]