The Collaborative International Dictionary of English v.0.48:

Comity \Com"i*ty\, n.; pl. Comities. [L. comitas, fr. comis
   courteous, kind.]
   Mildness and suavity of manners; courtesy between equals;
   friendly civility; as, comity of manners; the comity of
   States.
   [1913 Webster]

   Comity of nations (International Law), the courtesy by
      which nations recognize within their own territory, or in
      their courts, the peculiar institutions of another nation
      or the rights and privileges acquired by its citizens in
      their own land. By some authorities private international
      law rests on this comity, but the better opinion is that
      it is part of the common law of the land, and hence is
      obligatory as law.

   Syn: Civility; good breeding; courtesy; good will.
        [1913 Webster]

WordNet (r) 3.0 (2006):

comity
    n 1: a state or atmosphere of harmony or mutual civility and
         respect

Bouvier's Law Dictionary, Revised 6th Ed (1856):

COMITY. Courtesy; a disposition to accommodate.
     2. Courts of justice in one state will, out of comity, enforce the laws
of another state, when by such enforcement they will not violate their laws
or inflict. an injury on some one of their own citizens; as, for example,
the discharge of a debtor under the insolvent laws of one state, will be
respected in another state, where there is a reciprocity in this respect.
     3. It is a general rule that the municipal laws of a country do not
extend beyond its limits, and cannot be enforced in another, except on the
principle of comity. But when those laws clash and interfere with the rights
of citizens, or the laws of the countries where the parties to the contract
seek to enforce it, as one or the other must give way, those prevailing
where the relief is sought must have the preference. 2 Mart. Lo. Rep. N. S.
93; S. C. 2 Harr. Cond. Lo. Rep. 606, 609; 2 B. & C. 448, 471; 6 Binn. 353;
5 Cranch, 299; 2 Mass. 84; 6 Mass. 358; 7 Mart. Lo. R. 318. See Conflict of
Laws; Lex loci contractus.