What does immunise mean?
To immunise someone is to protect them against an infectious disease, normally by giving them a vaccine that prepares the immune system to recognise and resist a particular pathogen. The term is used extensively in public health, especially in connection with childhood vaccination programmes and the prevention of diseases such as measles, polio, and tetanus. It can also have a broader figurative meaning: a person or organisation that has been hardened by experience may be described as immunised against a particular danger. In British English, immunise is the standard spelling, while American English normally uses immunize. Although vaccination is the most familiar form of immunisation, the word can refer more broadly to any process that produces immunity. The distinction between the verb immunise and the adjective immune is important: the action creates or establishes resistance, while immune describes the resulting state.
verbTo protect a person or organism against an infectious disease by administering a vaccine or other means of stimulating immunity. It can also mean to make someone resistant to a harmful influence or threat.
- To protect against an infectious disease by giving someone a vaccine or otherwise stimulating immunity.
- To make someone or something resistant to a harmful influence, attack, or threat.
"The programme aims to immunise every child against measles before the next outbreak."
"Health workers travelled to remote communities to immunise residents against polio."
"Years of experience immunised the company against the risks of entering a volatile market."
Immunisation turns the body’s own immune system into a prepared defence—often before it ever encounters the disease.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of immunise
The word derives from immune, which comes from Latin immunis, meaning “free from” or “exempt from a duty or obligation.” The combining form in- expressed negation, while the Latin element munus referred to a service, duty, or obligation. The verb was formed on the pattern of immune plus the suffix -ise, and it developed in the medical sense before acquiring broader figurative uses.
Related word forms
How immunise is actually used
In British English, immunise is the usual spelling, though immunize is also understood. The verb is formal and most commonly refers to vaccination; when it means protection from a non-medical threat, the context usually makes that figurative sense clear.
Easily confused with immunise
To immunise a person is to make them immune, usually by administering a vaccine, whereas immune describes someone or something that already has resistance.
Immunise and immunize are the British and American spellings, respectively, of the same verb.