Where does the word vaccination come from?

According to legend, provincial doctor Edward Jenner once overheard a young dairymaid boasting: 

“I shall never have smallpox for I have had cowpox."​ 

This eventually lead to Jenner establishing that smallpox inoculation could provide protection against its far more lethal virological cousin. With a scientist's precision, Jenner called this process 'vaccination' - after vaccinia the Latin word for cowpox.

The cow connection proved great branding - the alleged vanity of the anonymous dairymaid has amused children for two hundred years. It also proved a gift to the original anti-vax movement, who were deeply suspicious of Jenner's devilish new life-saver.