The Collaborative International Dictionary of English v.0.48:

Sanguineness \San"guine*ness\, n.
   The quality of being sanguine.
   [1913 Webster]

WordNet (r) 3.0 (2006):

sanguineness
    n 1: feeling sanguine; optimistically cheerful and confident
         [syn: sanguinity, sanguineness]