The Collaborative International Dictionary of English v.0.48:

Correctness \Cor*rect"ness\, n.
   The state or quality of being correct; as, the correctness of
   opinions or of manners; correctness of taste; correctness in
   writing or speaking; the correctness of a text or copy.

   Syn: Accuracy; exactness; precision; propriety.
        [1913 Webster]

WordNet (r) 3.0 (2006):

correctness
    n 1: conformity to fact or truth [syn: correctness,
         rightness] [ant: incorrectness, wrongness]
    2: the quality of conformity to social expectations [ant:
       incorrectness]