What is Comity?

Legal Definition
In law, comity is "a practice among different political entities (as countries, states, or courts of different jurisdictions)" involving the "mutual recognition of legislative, executive, and judicial acts."
-- Wikipedia
Legal Definition
The legal principle that political entities (such as states, nations, or courts from different jurisdictions) will mutually recognize each other’s legislative, executive, and judicial acts. The underlying notion is that different jurisdictions will reciprocate each other’s judgments out of deference, mutuality, and respect.

In Constitutional law, the Comity Clause refers to Article IV, § 2, Clause 2 of the U.S. Constitution (also known as the Privileges and Immunities Clause), which ensures that “The Citizens of each State shall be entitled to all Privileges and Immunities of Citizens in the several States.”
Legal Definition
Courtesy; a disposition to accomodate.

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 Crancb, 299; 2 Mass. 84; 6 Mass. 358; 7 Mart. Lo. R. 318. See Conflict of Laws; Lex loci contractus.
-- Bouviers Law Dictionary
Legal Definition
Courtesy; complaisance; respect; a willingness to grant a privilege, not as a matter of right, but out of deference and good will.
See also
-- Black's Law Dictionary
Legal Definition
The recognition which one nation allows within its territory to the legislative, executive, or judicial acts of another nation. See 159 U. S. 113, 40 L. Ed. 95, 15 Sup. Ct Rep. 987.
-- Ballentine's Law Dictionary