Why is the ninth month called September?
1803, used by British physician Edward Jenner (1749-1823) for the technique he devised of preventing smallpox by injecting people with the cowpox virus (variolae vaccinae), from vaccine (adj.) "pertaining to cows, from cows" (1798), from Latin vaccinus "from cows," from vacca "cow" (bos being originally "ox," "a loan word from a rural dialect" according to Buck, who cites Umbrian bue). "The use of the term for diseases other than smallpox is due to Pasteur" [OED].
vaccination vac·ci·na·tion (vāk'sə-nā'shən)
Inoculation with a vaccine in order to protect against a particular disease.
A scar left on the skin by vaccinating.