The Collaborative International Dictionary of English v.0.48:

Algidity \Al*gid"i*ty\ ([a^]l*j[i^]d"[i^]*t[y^]), n.
   Chilliness; coldness; especially: (Med.), coldness and
   collapse. AS
   [1913 Webster]

WordNet (r) 3.0 (2006):

algidity
    n 1: prostration characterized by cold and clammy skin and low
         blood pressure