doc·tor / ˈdäktər/ • n. 1. a qualified practitioner of medicine; a physician. ∎  a qualified dentist or veterinary surgeon. ∎  inf. a person who gives advice or makes improvements: the script doctor rewrote the original.2. (Doctor) a person who holds a doctorate: he was made a Doctor of Divinity. ∎ short for Doctor of the Church. ∎ archaic a teacher or learned person: the wisest doctor is graveled by the inquisitiveness of a child.3. an artificial fishing fly. • v. [tr.] 1. change the content or appearance of (a document or picture) in order to deceive; falsify: the reports could have been doctored. ∎  alter the content of (a drink, food, or substance) by adding strong or harmful ingredients: he denied doctoring Stephen's drinks. ∎  Baseball tamper with (a ball) so as to affect its movement when pitched.2. [usu. as n.] (doctoring) inf. treat (someone) medically: he contemplated giving up doctoring.PHRASES: be (just) what the doctor ordered inf. be very beneficial or desirable under the circumstances: a 2-0 victory is just what the doctor ordered.DERIVATIVES: doc·tor·ly adj.

doctor originally (in Middle English) a person skilled in, and therefore entitled to teach or speak authoritatively on, any branch of knowledge, a learned person; the word comes via Old French from Latin doctor ‘teacher’, from docere ‘teach’.

From this developed the senses of Doctor of the Church, and (with capital initial) a person holding the highest university degree; the sense of doctor as an authority on medicine or surgery gave rise to the current meaning of a qualified medical practitioner.

The title Doctor of the Church was given to any of the early Christian theologians regarded as especially authoritative in the Western Church (particularly St Augustine of Hippo, St Jerome, St Ambrose, and St Gregory the Great), or those later so designated by the Pope (e.g. St Thomas Aquinas, St Teresa of Ávila).
the best doctors are Dr Diet, Dr Quiet, and Dr Merryman outlining an appropriate course of management for a sick person. The saying is recorded from the mid 16th century; a mid 15th-century source, Lydgate's Minor Poems, has, ‘Thre lechees [leeches, or doctors] consarue a mannys myht, First a glad hert…Temperat diet…And best of all, for no thyng take no thouht.’
Doctors' Commons (the site of) a London building occupied by the former College of Doctors of Laws, in which legal business relating to wills, marriage licences, and divorce proceedings was transacted. The name referred originally to the common table and dining-hall of the Association or College of Doctors of Civil Law in London, formed in 1509 by civilians entitled to plead in the Court of Arches.

"Doctor"

One of the spirit controls of the medium Stainton Moses (1839-1882). "Doctor" was said to have been the stoic philosopher Athenodorus, who instructed Emperor Tiberius in his youth. He was the supervisor of the philosophic teachings delivered through Moses and claimed to have invisibly attended him for 21 years. He was the alleged author of some of the Spirit Teachings published by Moses.

Doctor (dok-ter) n.
1. the title given to a recipient of a higher university degree than a Master's degree, usually a Doctor of Philosophy (PhD or DPhil) degree. The degree Medicinae Doctor (MD) is awarded by some British universities as a research degree to those with a first degree in medicine.

2. a courtesy title given to a qualified medical practitioner, i.e. one who has been registered by the General Medical Council.

doctor teacher; one highly proficient in a branch of learning or holding the highest university degree; spec. doctor of medicine, (hence) medical practitioner. XIV. — OF. doctour — L. doctor, -ōr-, teacher, f. doct-, pp. stem of docēre teach, causative corr. to discere learn (:- *di-dc-sc-).