The verb to inoculate is from Middle English inoculaten, which meant "to graft a scion" (a plant part to be grafted onto another plant); which in turn is from Latin inoculare, past participle inoculat-.
The Indian historian D.P. Agrawal suggests that the practice originated in India. A religious rite having this effect was attributed to the physician Dhanvantari, founder of the Vedic tradition, in about 1500 BCE.As with other medical customs, the inoculation was associated with a Hindu goddess. This ancient inoculation procedure featured in the BBC documentary What the Ancients Did for Us. In the 18th century Dr. J.Z. Holwell wrote the most detailed account for the college of Physicians in London, describing not only inoculation, but also showing that the Indians knew that microbes caused such diseases.
The practice was introduced to the west by Lady Mary Wortley Montagu (May 26, 1689 – August 21, 1762). Lady Montagu's husband, Edward Wortley Montagu, served as the British ambassador to the Ottoman Empire from 1716 to 1718. She witnessed firsthand the Turkish use of inoculation in Istanbul, and was greatly impressed: she had lost a brother to smallpox and bore facial scars from the disease herself. When a smallpox epidemic threatened England in 1721, she called on her physician to inoculate her daughter. She invited friends to see her daughter, including Sir Hans Sloane, the King's physician. Sufficient interest arose that Maitland gained permission to test inoculation at Newgate prison in exchange for their freedom on six prisoners due to be hanged, an experiment which was witnessed by a number of notable doctors.  All survived, and in 1722 the Prince of Wales' daughters received inoculations.
- 1: the introduction of a pathogen or antigen into a living organism to stimulate the production of antibodies
Inoculation is the placement of something that will grow or reproduce, and is most commonly used in respect of the introduction of a serum, vaccine, or antigenic substance into the body of a human or animal, especially to produce or boost immunity to a specific disease. It can also be used to refer to the communication of a disease to a living organism by transferring its causative agent into the organism, the implanting of microorganisms or infectious material into a culture medium such as a brewers vat or a petri dish, or the placement of microorganisms or viruses at a site where infection is possible.
Today the terms inoculation, vaccination and immunization are used more or less interchangeably and popularly refer to the process of artificial induction of immunity against various infectious diseases. The microorganism used in an inoculation is called the inoculant or inoculum.