The Collaborative International Dictionary of English v.0.48:

Traitorous \Trai"tor*ous\, a. [Cf. F. tra[^i]treux.]
   1. Guilty of treason; treacherous; perfidious; faithless; as,
      a traitorous officer or subject. --Shak.
      [1913 Webster]

   2. Consisting in treason; partaking of treason; implying
      breach of allegiance; as, a traitorous scheme.
      [1913 Webster] -- Trai"tor*ous*ly, adv. --
      Trai"tor*ous*ness, n.
      [1913 Webster]

WordNet (r) 3.0 (2006):

traitorousness
    n 1: disloyalty by virtue of subversive behavior [syn:
         treason, subversiveness, traitorousness]