The Collaborative International Dictionary of English v.0.48:

Legality \Le*gal"i*ty\ (l[-e]*g[a^]l"[i^]*t[y^]), n. [Cf. LL.
   legalitas, F. l['e]galit['e]. Cf. Loyalty.]
   1. The state or quality of being legal; conformity to law.
      [1913 Webster]

   2. (Theol.) A conformity to, and resting upon, the letter of
      the law.
      [1913 Webster]

WordNet (r) 3.0 (2006):

legality
    n 1: lawfulness by virtue of conformity to a legal statute [ant:
         illegality]