Meaning

noun taking a vaccine as a precaution against contracting a disease

noun the scar left following inoculation with a vaccine

originFrom vaccinia, a cowpox infection. Ultimately from Latin vacca (“cow”). Coined by Edward Jenner (1749-1823) in 1798. Jenner infected people with weakened cowpox viruses (vaccinia), to immunise them against smallpox. It is now known that vaccinia and cow pox are separate conditions, but at the time of Jenner, they were considered the same condition.

Etymology from Wiktionary, CC BY-SA 3.0