What is a Doctor of the Church?

In Roman Catholicism, this title is given to a saint from whose writings the whole Christian Church is held to have derived great advantage and to whom "eminent learning" and "great sanctity" have been attributed by a proclamation of a pope or of an ecumenical council. This honor is given rarely, only posthumously, and only after canonization. ... The Roman Catholic Church has to date named 33 Doctors of the Church. Among these 33 are 25 from the West and 8 from the East; 3 women; 18 bishops, 29 priests, 1 deacon, 2 nuns, 1 lay woman; 24 from Europe, 3 from Africa, 6 from Asia. -- http://en.wikipedia.org/wiki/Doctor_of_the_Church