The Collaborative International Dictionary of English v.0.48:

Sanity \San"i*ty\, n. [L. sanitas, from sanus sound, healthy.
   See Sane.]
   The condition or quality of being sane; soundness of health
   of body or mind, especially of the mind; saneness.
   [1913 Webster]

WordNet (r) 3.0 (2006):

sanity
    n 1: normal or sound powers of mind [syn: sanity, saneness]
         [ant: insanity]