The Collaborative International Dictionary of English v.0.48:

Sopor \So"por\, n. [L.] (Med.)
   Profound sleep from which a person can be roused only with
   difficulty.
   [1913 Webster]

WordNet (r) 3.0 (2006):

sopor
    n 1: a torpid state resembling deep sleep [syn: sleep,
         sopor]