The Collaborative International Dictionary of English v.0.48:

Chilblain \Chil"blain`\, chilblains \chil"blains\, n. [Chill +
   Blain.]
   A blain, sore, or inflammatory swelling of the feet or hands,
   produced by exposure to cold, and attended by itching, pain,
   and sometimes ulceration.

   Syn: pernio.
        [1913 Webster + WordNet 1.5]

WordNet (r) 3.0 (2006):

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