antibody
Americannoun
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any of numerous Y -shaped protein molecules produced by B cells as a primary immune defense, each molecule and its clones having a unique binding site that can combine with the complementary site of a foreign antigen, as on a virus or bacterium, thereby disabling the antigen and signaling other immune defenses. Ab
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antibodies of a particular type collectively.
noun
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Any of numerous proteins produced by B lymphocytes in response to the presence of specific foreign antigens, including microorganisms and toxins. Antibodies consist of two pairs of polypeptide chains, called heavy chains and light chains, that are arranged in a Y-shape. The two tips of the Y are the regions that bind to antigens and deactivate them.
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Also called immunoglobulin
Closer Look
Like other vertebrates, humans possess an effective immune system that uses antibodies to fight bacteria, viruses, and cancer cells. Antibodies are complex, Y-shaped protein molecules. The immune system's B lymphocytes, which are produced by the bone marrow, develop into plasma cells that can generate a huge variety of antibodies, each one capable of combining with and destroying an antigen, a foreign molecule. Antibodies react to very specific characteristics of different antigens, binding them to the top ends of their Y formation. Once the antibody and antigen combine, the antibodies deactivate the antigen or lead it to macrophages(a kind of white blood cell) that ingest and destroy it. High numbers of a particular antibody may persist for months after an invasion, eventually diminishing. However, the B cells can quickly manufacture more of the same antibody if exposure to the antigen recurs. Vaccines work by “training” B cells to recognize and react quickly to potential disease molecules.
Other Word Forms
Noun Inflected Forms
Etymology
Origin of antibody
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Explanation
An antibody is a protein made by the body that latches onto foreign bacteria and viruses to make them ineffective. Each antibody is designed to target a particular opponent. A powerful part of the body’s immune system, an antibody is produced when the body senses an invader — called an antigen that it doesn’t think should be there. The body then sends out the antibody to neutralize it. Don’t think of an antibody as being anti or “against” your body; think of the body in the word antibody as the antigen, or foreign body that is being fought. Known antibodies have been especially useful in the creation of vaccines.
Vocabulary lists containing antibody
This Week In Words: May 3–9, 2020
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Florida's B.E.S.T. Common Prefixes: ant-, anti-
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The ACT Science Test: Biology Review 2
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Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
See Examples For:
In happier news, rising case counts have jump-started research into drugs that could treat people who do get sick, including antibody and antiviral therapies.
From Slate ● Jul. 24, 2026
The findings show that the antibody performed as the researchers intended.
From Science Daily ● Jul. 21, 2026
Summit’s drug, a so-called bispecific antibody, aims to evolve that strategy by activating the immune system while simultaneously starving the tumor.
From The Wall Street Journal ● Jun. 6, 2026
Roche’s anti-amyloid antibody trontinemab has a fragment that mimics the natural iron-shuttling molecule known as transferrin.
From Barron's ● Jun. 3, 2026
That’s the principle of vaccination: to stimulate our antibody production without our having to go through the actual experience of the disease, by inoculating us with a dead or weakened strain of microbe.
From "Guns, Germs, and Steel: The Fates of Human Societies" by Jared M. Diamond
Antivenom is manufactured by providing a small dose of the harvested venom into either a sheep or horse, which trigger’s the animal’s immune system into creating antibodies.
From Los Angeles Times ● Jul. 21, 2026
These participants generally developed higher levels of antibodies against SARS-CoV-2 and showed stronger neutralizing activity against several viral variants.
From Science Daily ● Jul. 21, 2026
Van Nunen's biggest concern, though, is the 85% of people who have the allergy without knowing it – people who have developed the antibodies but who do not react after eating meat.
From BBC ● Jul. 20, 2026
"The average Brazilian did not have antibodies against betting," he said.
From Barron's ● Jul. 17, 2026
Against other illnesses, though—including measles, mumps, rubella, pertussis, and the now defeated smallpox—our antibodies stimulated by one infection confer lifelong immunity.
From "Guns, Germs, and Steel: The Fates of Human Societies" by Jared M. Diamond
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
