(Lat. from doceo, I teach), a person who has passed all the degrees of a faculty, and is empowered to teach or practise the same. Hence the terms doctor in divinity, doctor in physic, doctor of laws.

The establishment of the doctorate, as now in use amongst us, is ordinarily attributed to Irnerius, who himself drew up the formulary. The first ceremony of this kind was performed at Bologna, in the person of Bulgarus, who began to profess the Roman law, and on that occasion was solemnly promoted to the doctorate, that is, installed juris utrinque doctor. But the custom was soon transferred from the faculty of law to that of theology; the first instance of which was given in the university of Paris, where Peter Lombard and Gilbert de la Portree, the two leading divines of those days, were created doctors in theology, sacrae theologiae doctores.

Spelman conceives the title of doctor not to have been in use till after the publication of Lombard's Sentences, about the year 1140. Others, however, go much higher, holding Bede to have been the first doctor at Cambridge, and John de Beverley at Oxford, where the latter died in 721. But Spelman contends that doctor was not the name of any title or degree in England till the reign of King John, that is, about the year 1207. As to the qualifications or course of study necessary to obtain the degree of doctor in the different faculties of theology, law, and medicine, see Universities.

Doctor of the Law, a title of honour among the Jews. The investiture, if we may so speak, of this order, was performed by putting a key and a table book in their hands; and it was in allusion to this ceremony, some authors imagine, that our Saviour, when speaking of the doctors of the law, says—"Wo unto you, lawyers! for ye have taken away the key of knowledge; ye enter not in yourselves, and them that were entering in ye hindered."

Doctor of the Church, a title given to certain of the fathers whose doctrines and opinions have been the most generally followed and authorized. We usually reckon four doctors of the Greek Church and three of the Latin. The former are, St Athanasius, St Basil, St Gregory Nazianzen, and St Chrysostom; the latter are St Jerome, St Augustin, and Gregory the Great. In the Roman breviary there is a particular office for the doctors, which only differs from that of the confessors by the anthem of the Magnificat and the lessons.

Doctor is also an appellation adjoined to a specific epithet, expressing the merit of some eminent schoolman. Thus, Alexander Hales is called the irrefragable doctor; Thomas Aquinas, the angelic doctor; St Bonaventure, the seraphic doctor; John Duns Scotus, the subtile doctor; Raimond Lully, the illuminated doctor; Roger Bacon, the admirable doctor; and so on.