The Collaborative International Dictionary of English v.0.48:

Resupine \Re`su*pine"\, a. [L. resupinus; pref. re- re- +
   supinus bent backward, supine.]
   Lying on the back; supine; hence, careless. --Sir K. Digby.
   [1913 Webster]

         He spake, and, downward swayed, fell resupine,
         With his huge neck aslant.               --Cowper.
   [1913 Webster]

WordNet (r) 3.0 (2006):

resupine
    adj 1: lying face upward [syn: supine, resupine]