What is the X in X-mas?
mid-15c., "implant a bud into a plant," from Latin inoculatus, past participle of inoculare "graft in, implant," from in- "in" (see in- (2)) + oculus "bud," originally "eye" (see eye (n.)). Meaning "implant germs of a disease to produce immunity" first recorded (in inoculation) 1714, originally in reference to smallpox. After 1799, often used in sense of "to vaccine inoculate." Related: Inoculated; inoculating.
inoculate in·oc·u·late (ĭ-nŏk'yə-lāt')
v. in·oc·u·lat·ed, in·oc·u·lat·ing, in·oc·u·lates
To introduce a serum, a vaccine, or an antigenic substance into the body of a person or an animal, especially as a means to produce or boost immunity to a specific disease.
To implant microorganisms or infectious material into or on a culture medium.
To communicate a disease to a living organism by transferring its causative agent into the organism.