doctoryoudaoicibaDictYouDict[doctor 词源字典]
doctor: [14] Doctor, doctrine, and document all go back ultimately to the Latin verb docēre ‘teach’. This in turn was a descendant of an Indo-European base *dok-, *dek- which also produced Greek dokein ‘seem, think’ (source of English dogma [17], orthodox, and paradox) and didáskein ‘learn’ (source of English didactic [17]) and Latin decere ‘be fitting or suitable’ (source of English decent, decorate, and dignity) and dexter (source of English dextrous).

Latin doctor was derived from doctus, the past participle of docēre, and came into English via Old French doctour. It originally meant ‘teacher’, and the main modern sense of ‘medical practitioner’, although sporadically recorded in Middle English, did not become firmly established until the late 16th century. Latin doctrīna ‘teaching, learning’, a derivative of Latin doctor, produced English doctrine [14].

Latin documentum, which came directly from docēre, originally meant ‘lesson’, but in medieval Latin its signification had passed through ‘written instruction’ to ‘official paper’. English acquired it as document [15]. The derivative documentary is 19th-century.

=> dainty, decent, decorate, dextrous, didactic, dignity, doctrine, document, dogma, orthodox, paradox[doctor etymology, doctor origin, 英语词源]
doctor (n.)youdaoicibaDictYouDict
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" (see decent).

Meaning "holder of highest degree in university" is first found late 14c.; as is that of "medical professional" (replacing native leech (n.2)), though this was not common till late 16c. The transitional stage is exemplified in Chaucer's Doctor of phesike (Latin physica came to be used extensively in Medieval Latin for medicina). Similar usage of the equivalent of doctor is colloquial in most European languages: Italian dottore, French docteur, German doktor, Lithuanian daktaras, though these are typically not the main word in those languages for a medical healer. For similar evolution, see Sanskrit vaidya- "medical doctor," literally "one versed in science." German Arzt, Dutch arts are from Late Latin archiater, from Greek arkhiatros "chief healer," hence "court physician." French médecin is a back-formation from médicine, replacing Old French miege, from Latin medicus.
doctor (v.)youdaoicibaDictYouDict
1590s, "to confer a degree on," from doctor (n.). Meaning "to treat medically" is from 1712; sense of "alter, disguise, falsify" is from 1774. Related: Doctored; doctoring.