inoculate (v.)
mid-15c., "implant a bud into a plant," from Latin inoculatus, past participle of inoculare "graft in, implant a bud or eye of one plant into another," from in- "in" (from PIE root *en "in") + oculus "bud," originally "eye" (from PIE root *okw- "to see"). Meaning "implant germs of a disease to produce immunity" is from inoculation, originally in reference to smallpox, after 1799, often used in sense of "to inoculate with a vaccine." Related: Inoculated; inoculating.