c. 1300, “Church father,” from Old French doctour, from Medieval Latin doctor “religious teacher, adviser, scholar,” in classical Latin “teacher,” agent noun from docere “to show, teach, cause to know,” originally “make to appear right,” causative of decere “be seemly, fitting,” from PIE root *dek– “to take, accept.”
“doctor | Origin and meaning of doctor by Online Etymology Dictionary,” Online Etymology Dictionary, accessed 9th May 2018, https://www.etymonline.com/word/doctor