Hastings' Dictionary of the Bible (1898)
DOCTOR. Doctors or teachers of the law were those who made it their business or profession to teach the Law of Moses, and they were in great repute among the Jews. Luke 2:46. Some have distinguished the scribes from the doctors by supposing that the former wrote their opinions, while the latter taught extemporaneously. The doctors were generally of the sect of the Pharisees, perhaps always. Luke 5:17.
The word "teachers" came into early use among Christians as a title to those who taught the doctrines of the faith, 1 Cor 12:28, and hence was afterward applied to those who became eminent for their learning and aptness in teaching.