What is Consul?

Legal Definition
Consul (abbrev. cos.; Latin plural consules) was the title of one of the chief magistrates of the Roman Republic, and subsequently a somewhat significant title under the Roman Empire. The title was also used in other city states and also revived in modern states, notably in the First French Republic. The relating adjective is consular, from the consularis.
-- Wikipedia
Legal Definition
In Roman law. During the republic, the name "consul" was given to the chief executive magistrate, two of whom were chosen annually. The office was continued under the empire, but its powers and prerogatives were greatly reduced. The name is supposed to have been derived from consulo, to consult, because these officers consulted with the senate on administrative measures. In old English law. An ancient title of an earl. In international law. An officer of a commercial character, appointed by the dlf-ferent states to watch over the mercantile interests of the appointing state and of its subjects in foreign countries. There are usually a number of consuls in every maritime country, and they are usually subject to a chief consul, who is called a "consui general." Schunior v. Russell, 83 Tex. 83, 18 ,S. W. 484; Seidel v. Peschkaw, 27 N. J. Law, 427; Sartori v. Hamilton, 13 N. J. Law, 107; The Anne, 3 Wheat 445, 4 L. Ed. 428. The word "consul" has two meanings:

(1) It denotes an officer of a particular grade in the consular service;

(2) it has a broader generic sense, embracing all consular officere, Dainese v. U. S., 15 Ct Cl. 64. The official designations employed throughout this title shall be deemed to have the following meanings, respectively: First. "Consul general, "consul," and "commercial agent" shall be deemed to denote full, principal, and permanent consular officers, as distinguished from subordinates and substitutes. Second. "Deputy-consul" and "consular agent" shall be deemed to denote consular officers subordinate to such principals, exercising the powers and performing the duties within the limits of their consulates or commercial agencies respectively, the former at the same ports or places and the latter at ports or places different from those at which such principals are located respectively. Third. "Viceconsuls" and "vice-commercial agents" shall be deemed to denote consular officers who shall be substituted, temporarily, to fill the places of consuls general, consuls, or commercial agents, when they shall be temporarily absent or relieved from duty. Fourth. "Consular officer" shall be deemed to include consuls general, consuls, commercini agents, deputy-consuls, viceconsuls, vice-commercial agents, and consular agents, and none others. Fifth. "Diplomatio officer" shall be deemed to include ambassadors, envoys extraordinary, ministers plenipotentiary, ministers resident, commissioners, charges d'affaires, agents, and secretaries of legation, and none others. Rev. St. U. S. ยง 1674 (U. S. Comp. St 1901, p. 1150.)
-- Black's Law Dictionary
Legal Definition
A government agent in a foreign place to protect the citizens and trade of his country. See 103 U. S. 261, 26 L. R. A. 539.
-- Ballentine's Law Dictionary