noun
vaccine
A preparation that trains the immune system to protect against a disease.
Where it comes from
Vaccine ordinarily means a preparation that trains the immune system to protect against a disease. Vaccine traces to Latin vacca, cow. Edward Jenner's 1798 account used the New Latin variolae vaccinae for cowpox, central to his work on protection against smallpox. Terms for cowpox material and the procedure soon followed.
How the meaning developed
Vaccine then broadened beyond cowpox and smallpox to preparations against many diseases.
Sources
Definitions adapted from Open English WordNet where applicable. License and attribution. Word-history text comes from Lexifour’s sourced social research; pages are assembled automatically, not individually fact-checked on every update.
Updated 2026-10-05. Report a correction.