What is Advocate?

Legal Definition
An advocate is a type of professional person in several different legal systems and it is also a commonly used honorific for remarkable lawyers, such as in "Adv. Sir Alberico Gentili". The broad equivalent in many English law-based jurisdictions can be a barrister. However, in Scottish, South African, Italian, French, Spanish, Portuguese, Scandinavian, Polish, South Asian and South American jurisdictions, advocate is also a word to indicate lawyers of superior classification.
-- Wikipedia
Legal Definition
1. Someone who actively promotes the interests of another person or enterprise. This may involve filing claims, defending against the claims of others, and persuading other parties (e.g., government officials) to act favorably towards the relevant person or enterprise. Pronounced "ad-vuh-kit."

2. To act as the type of person defined above. Pronounced "ad-vuh-kate."
Legal Definition
Civil and ecclesiastical law. 1. An officer who maintains or de fends the rights of his client in the same manner as the counsellor does in the common law.

2. Lord Advocate. An, officer of state in Scotland, appointed by the king, to advise about the making and executing the law, to prosecute capital crimes, &c.

3. College or faculty of advocates. A college consisting of 180 persons, appointed to plead in. all actions before the lords of sessions.

4. Church or ecclesiastical advocates. Pleaders appointed by the church to maintain its rights.

5. – 2. A patron who has the advowson or presentation to a church. Tech. Dict.; Ayl. Per. 53; Dane Ab. c.,31, 20. See Counsellor at law; Honorarium.
-- Bouviers Law Dictionary
Legal Definition
One who assists, defends or pleads for another; one who renders legal advice and aid and pleads the cause of another before a court. A person learned in the law, and duly admitted to practice, who assists his client with advice, and pleads for him In open court. Holthouse. The College or Faculty of Advocates is a corporate body in Scotland, consisting of the members of the bar In Edinburgh. A large portion of its members are not active practitioners, however. 2 Bankt. Inst. 486. In the civil and ecclesiastical law. An officer of the court, learned in the law, who is engaged by a suitor to maintain or defend his cause.
See also
-- Black's Law Dictionary
Legal Definition
A barrister; one who may plead causes in a court.
-- Ballentine's Law Dictionary