What is Sovereignty?

Legal Definition
Sovereignty is understood in jurisprudence as the full right and power of a governing body to govern itself without any interference from outside sources or bodies. In political theory, sovereignty is a substantive term designating supreme authority over some polity. It is a basic principle underlying the dominant Westphalian model of state foundation.

Derived from Latin through French souveraineté, its attainment and retention, in both Chinese and Western culture, has traditionally been associated with certain moral imperatives upon any claimant.
-- Wikipedia
Legal Definition
The union and exercise of all human power possessed in a state; it is a combination of all power; it is the power to do everything in a state without accountability; to make laws, to execute and to apply them: to impose and collect taxes, and, levy, contributions; to make war or peace; to form treaties of alliance or of commerce with foreign nations, and the like. Story on the Const. §207.

2. Abstractedly, sovereignty resides in the body of the nation and belongs to the people. But these powers are generally exercised by delegation.

3. When analysed, sovereignty is naturally divided into three great powers; namely, the legislative, the executive, and the judiciary; the first is the power to make new laws, and to correct and repeal the old; the second is the power to execute the laws both at home and abroad; and the last is the power to apply the laws to particular facts; to judge the disputes which arise among the citizens, and to punish crimes.

4. Strictly speaking, in our republican forms of government, the absolute sovereignty of the nation is in the people of the nation; (q. v.) and the residuary sovereignty of each state, not granted to any of its public functionaries, is in the people of the state. (q. v.) 2 Dall. 471; and vide, generally, 2 Dall. 433, 455; 3 Dall. 93; 1 Story, Const. §208; 1 Toull. n. 20 Merl. Reper. h. t.
-- Bouviers Law Dictionary
Legal Definition
The possession of sovereign power; supreme political authority; paramount control of the constitution and frame of government and its administration; the self-sufficient source of political power, from which all specific political powers are derived; the international independence of a state, combined with the right and power of regulating its internal affairs without foreign dictation; also a political society or state, which is sovereign and independent. See Chisholm v. Georgia, 2 Dali. 455, 1 L. Ed. 440; Union Bank v. Hill, 3 Cold. (Tenn.) 325; Moore v. Shaw, 17 Cal. 218, 79 Am. Dec. 123. "The freedom of the nation has its correlate in the sovereignty of the nation. Political sovereignty is the assertion of the self-determinate will of the organic people, and in this there is the manifestation of its freedom. It is in and through the determination of its sovereignty that the order of the nation is constituted and maintained." Mulford, Nation, p. 129. "If a determinate human superior, not in a habit of obedience to a like superior, receive habitual obedience from the bulk of a given society, that determinate superior is sovereign in that society, and the society (including the superior) is a society political and independent." Aust. Jur.
-- Black's Law Dictionary
Legal Definition
That public authority which commands in civil society, and orders and directs what each citizen is to perform to obtain the end of its institution. See 101 Am. St. Rep. 158, note.
-- Ballentine's Law Dictionary