Doctor is an academic title that originates from the Latin word of the same spelling and meaning. The word is originally an agentive noun of the Latin verb docēre dɔˈkeːrɛ 'to teach'. It has been used as an academic title in Europe since the 13th century, when the first doctorates were awarded at the University of Bologna and the University of Paris.
Having become established in European universities, this usage spread around the world. Contracted "Dr" or "Dr.", it is used as a designation for a person who has obtained a doctorate (commonly a PhD/DPhil). In past usage, the term could be applied to any learned person. In many parts of the world today it is also used by medical practitioners, regardless of whether they hold a doctoral-level degree.
The doctorate (doceō) appeared in medieval Europe as a license to teach (licentia docendi) at a medieval university. Its roots can be traced to the early church, when the term "doctor" referred to the Apostles, church fathers and other Christian authorities who taught and interpreted the Bible. The right to grant a licentia docendi was originally reserved to the church which required the applicant to pass a test, take an Oath of allegiance and pay a fee. The Third Council of the Lateran of 1179 guaranteed the access — now largely free of charge — of all able applicants, who were, however, still tested for aptitude by the ecclesiastic scholastic. This right remained a bone of contention between church authorities and the slowly emancipating universities, but was granted by the pope to the University of Paris in 1213, when it became a universal license to teach (licentia ubiquie docendi). However, while the licentia continued to hold more prestige than the bachelor's degree (Baccalaureus), it was eventually positioned below the Magister and the doctorate, which became the only titles with which one could teach.
The earliest doctoral degrees — in theology, law, and medicine — reflected the historical separation of university study into these three fields.