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]

Moby Thesaurus II by Grady Ward, 1.0:

39 Moby Thesaurus words for "legality":
   admissibility, admissibleness, allowableness, defensibility,
   drumhead justice, dueness, equitableness, equity, evenhandedness,
   give-and-take, justice, justifiability, justifiableness,
   justification, justness, lawfulness, legitimacy, licitness,
   measure for measure, meetness, nemesis, permissibility,
   permissibleness, poetic justice, properness, propriety,
   retributive justice, right, rightfulness, rightness, rude justice,
   sanctionableness, scales of justice, summary justice, validity,
   warrantability, warrantableness, warrantedness, what is right