[ im-yuh-nuh-zey-shuhn, ih-myoo- ]
/ ˌɪm yə nəˈzeɪ ʃən, ɪˌmyu- /
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the fact or process of becoming immune, as against a disease.
Finance. a method of protection against fluctuating bond interest rates by investing in securities having different yields and terms.


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Origin of immunization

First recorded in 1890–95; immunize + -ation

OTHER WORDS FROM immunization

hy·per·im·mu·ni·za·tion, nounnon·im·mu·ni·za·tion, noun
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023


What’s the difference between immunization, vaccination, and inoculation?

In the context of medicine, the words immunization, vaccination, and inoculation are often used in overlapping ways, and for good reason—they all involve the process of introducing a substance (especially a vaccine) into a person’s body with the goal of preventing them from getting a particular disease.

Vaccination is the most specific of the three terms, because it always involves introducing a vaccine, which usually consists of a small amount of a killed, weakened, or otherwise modified version of a disease (such as a virus or bacterium). While inoculation has other meanings outside the context of medicine, in modern healthcare it’s typically used interchangeably with vaccination (though it’s used less commonly).

Immunization is slightly different—it refers to the process of providing immunity from a specific disease. While the goal of vaccinating someone is often to immunize them, not all vaccines provide permanent immunity. Some vaccines provide what amounts to long-term immunity, while others only lead to a temporary protection, after which the body “forgets” how to make certain antibodies. In these cases, a booster shot or dose is often required, consisting of a follow-up vaccination to boost or renew the protection gained from the earlier vaccination.

Both vaccination and inoculation can refer to a shot or dose, as opposed to the process of providing or receiving such doses, as in I’m scheduled to get a vaccination on Friday. The word immunization can be used in the same way to refer to such a vaccination when it’s one that provides immunity, as in Have you received all of your immunizations?

Want to learn more? Read the full breakdown of the difference between immunize, vaccinate, and inoculate.

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The words immunization, vaccination, and inoculation can be correctly used in some overlapping ways.

How to use immunization in a sentence

Scientific definitions for immunization

[ ĭm′yə-nĭ-zāshən ]

The process of inducing immunity to an infectious organism or agent in an individual or animal through vaccination.
A vaccination that induces immunity. A recommended schedule of immunizations for infants and young children includes vaccines against diphtheria, polio, tetanus, measles, mumps, and rubella.

Other words from immunization

immunize verb
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

Cultural definitions for immunization


The process of inducing immunity, usually through inoculation or vaccination.

notes for immunization

Frequently, schoolchildren are required by state law to be immunized against certain diseases. Because of such widespread immunization, many diseases that used to be fairly common, including smallpox, tetanus, and whooping cough, have become rare.
The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.