immunize

American  

[im-yuh-nahyz, ih-myoo-nahyz] / ˈɪm yəˌnaɪz, ɪˈmyu naɪz /

especially British, immunise

verb (used with object)

immunized, immunizing

1. to make immune, or protected from a disease or the like.

   They are organizing a massive health campaign to immunize millions of children.

   George Washington's army immunized its soldiers against smallpox.

2. to shield, exempt, or protect.

   There is no moral or legal basis for immunizing victorious nations from scrutiny over their actions in a war.

3. Law. to grant (a witness) exemption from criminal prosecution, legal liability, or punishment on certain conditions.

   In exchange for her testimony, the court agreed to immunize the witness against prosecution for criminal activities committed during the relevant period.

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immunize British  

/ ˈɪmjʊˌnaɪz /

verb

1. to make immune, esp by inoculation

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Usage

What’s the difference between immunize, vaccinate, and inoculate? In the context of medicine, immunize, inoculate, and vaccinate are often used in overlapping ways, and for good reason—they all involve introducing a substance (especially a vaccine) into a person’s body with the goal of preventing them from getting a particular disease. Vaccinate 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 inoculate has other meanings outside the context of medicine, in modern healthcare it’s typically used interchangeably with vaccinate (though it’s used less commonly). Immunize is slightly different—it means to provide 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 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. Want to learn more? Read the full breakdown of the difference between immunize, vaccinate, and inoculate.

Other Word Forms

• hyperimmunize
  verb (used with object)
• immunization
  noun
• immunizer
  noun
• overimmunize
  verb (used with object)

Etymology

Origin of immunize

First recorded in 1890–95; immune + -ize

Explanation

To immunize someone is to give them a vaccine that protects them against disease. A child's pediatrician can immunize her against measles, polio, and mumps, among many other illnesses. Vaccines work by arming your immune system against being infected — in other words, they produce immunity, or immunize you. In some cases, being exposed to a disease can also immunize you; if you've had chicken pox, you are most likely immune to it and won't get it again. There is also a legal meaning of immunize, "To make legally immune," or "to protect from being prosecuted in court." The Latin root, immunis, means "exempt" or "free."

Example Sentences

Unfortunately for the bulls, robust projected earnings growth doesn’t immunize the market from major declines.

From MarketWatch • Jan. 13, 2026

You can think of many areas where merely sitting abroad is not going to immunize you from the reach of American prosecution.

From Slate • Jan. 7, 2026

After Epstein’s death, the men used their executor roles—controlling both victims’ compensation and access to records—to try to immunize themselves from personal lawsuits, according to court filings.

From The Wall Street Journal • Nov. 23, 2025

But RSV, the leading cause of infant hospitalization nationwide, presents particular risk for the youngest babies, a major reason health experts recommend pregnant women either get vaccinated near their delivery date or immunize their newborns.

From Los Angeles Times • Oct. 30, 2025

Being black did not immunize us from history’s logic or the lure of the Dream.

From "Between the World and Me" by Ta-Nehisi Coates

Related Words

• inoculate
• protect
• vaccinate