c.1300, "Church father," from O.Fr. doctour, from M.L. doctor "religious teacher, adviser, scholar," from L. doctor "teacher," from doct- stem of docere "to show, teach," originally "make to appear right," causative of decere "be seemly, fitting" (see decent). Familiar form doc first recorded c.1850. Meaning of "holder of highest degree in university" is first found late 14c.; as is that of "medical professional," though this was not common till late 16c. Verb sense of "alter, disguise, falsify" is first recorded 1774.