doctor

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A person who is licensed to practice medicine and has trained at a school of medicine, chiropractic, optometry, podiatry, dentistry, or veterinary medicine.
• noun A practitioner of alternative medicine or folk medicine who does not have traditional medical credentials.
• noun A person who has earned the highest academic degree, usually a PhD, awarded by a college or university in a specified discipline.
• noun A person awarded an honorary degree by a college or university.
• noun Used as a title and form of address for a person holding the degree of doctor.
• noun Roman Catholic Church An eminent theologian.
• noun A rig or device contrived for remedying an emergency situation or for doing a special task.
• intransitive verb Informal To give medical treatment to.
• intransitive verb To repair, especially in a makeshift manner; rig.
• intransitive verb To falsify or change in such a way as to make favorable to oneself.
• intransitive verb To add ingredients so as to improve or conceal the taste, appearance, or quality of.
• intransitive verb To alter or modify for a specific end.
• intransitive verb Baseball To deface or apply a substance to (the ball) in violation of the rules in order to throw a pitch with extraordinary movement.
• intransitive verb To practice medicine.

from The Century Dictionary.

• noun A teacher; an instructor; a learned man; one skilled in a learned profession.
• noun In a university, one who has passed all the degrees of a faculty, and is thereby empowered to teach the subjects included in the faculty; a person who has received the highest degree in a faculty: as, a doctor in divinity.
• noun Specifically A person duly licensed to practise medicine; a physician; one whose occupation is to cure diseases.
• noun A minor part of certain pieces of machinery employed in regulating the feed or in removing surplus material; specifically, the roller in a power printing-press which serves as a conductor of ink to the distributing rollers (see crab-roller, drop-roller): as, a color-doctor; a cleaning-doctor; a lint-doctor, etc.
• noun An auxiliary steam-engine; a donkey-engine.
• noun In wine-making: A liquor used to mix with inferior wine to make it more palatable, or to give it a resemblance to a better wine.
• noun A liquor used to darken the color of wine, as boiled must mixed with pale sherry to produce brown sherry. See shcrry, mosto, and must.
• noun A translation of a local name in North Africa of the bird Emberiza striolata. See the extract.
• noun Same as doctor-fish.
• noun plural False or doctored dice.
• noun In some American universities, a degree superior to that of master of arts. Abbreviated Ph. D. See above, 2.
• noun In angling, a name applied to several artificial flies: as, the blue doctor, the silver doctor, etc.
• noun A boiler feed-pump such as has been preferred on the western rivers of the United States.
• noun The cook of a merchant vessel; also, the cook of a lumber-camp.
• To treat, as a doctor or physician; treat medicinally; apply medicines for the cure of; administer medicine or medical treatment to: as, to doctor a disease; to doctor a patient.
• To repair; mend; patch up.
• To confer the degree of doctor upon.
• To disguise by mixture or manipulation; especially, to alter for the purpose of deception; give a false appearance to; adulterate; cook up; tamper with: as, to doctor wine or an account.
• To practise physic.
• To receive medical treatment; take medicine: as, to doctor for ague.

from the GNU version of the Collaborative International Dictionary of English.

• intransitive verb colloq. To practice physic.
• transitive verb colloq. To treat as a physician does; to apply remedies to; to repair.
• transitive verb To confer a doctorate upon; to make a doctor.
• transitive verb Slang To tamper with and arrange for one's own purposes; to falsify; to adulterate
• noun obsolete A teacher; one skilled in a profession, or branch of knowledge; a learned man.
• noun An academical title, originally meaning a man so well versed in his department as to be qualified to teach it. Hence: One who has taken the highest degree conferred by a university or college, or has received a diploma of the highest degree. Such diplomas may confer an honorary title only.
• noun One duly licensed to practice medicine; a member of the medical profession; a physician.
• noun Any mechanical contrivance intended to remedy a difficulty or serve some purpose in an exigency
• noun (Zoöl.), Prov. Eng. The friar skate.
• noun See under Commons.
• noun physic, medicine.
• noun (Zoöl.) any fish of the genus Acanthurus; the surgeon fish; -- so called from a sharp lancetlike spine on each side of the tail. Also called barber fish. See Surgeon fish.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A person who has attained a doctorate, such as a Ph.D. or Th.D. or one of many other terminal degrees conferred by a college or university.