antibody
Americannoun
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antibodies
plural
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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
Compare meaning
How does antibody compare to similar and commonly confused words? Explore the most common comparisons:
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:
AstraZeneca is testing its Datroway antibody drug conjugate in combination with its PD-L1 medicine Imfinzi for lung cancer in a late-stage clinical trial.
From The Wall Street Journal ● Sep. 30, 2026
Human clinical trials of their antibody drugs against bird flu and other viruses in the flu family are planned for next year.
From The Wall Street Journal ● Sep. 28, 2026
Some people are AnWj negative because of inherited MAL changes, while others can lose AnWj expression because of disease and develop an antibody against a marker their cells previously carried.
From Science Daily ● Sep. 19, 2026
That matters because finding compatible blood for someone with an antibody against a marker present in more than 99.9% of people can be extraordinarily difficult.
From Science Daily ● Sep. 19, 2026
It has recently been learned that the genes for the marking of self by cellular antigens and those for making immunologic responses by antibody formation are closely linked.
From "The Lives of a Cell" by Lewis Thomas
The sugar, found in most mammals but not in humans, prompts the antibodies that trigger an allergic reaction.
From Los Angeles Times ● Oct. 4, 2026
My dermatologist in Washington, D.C., didn’t even know a blood test could measure alpha-gal antibodies.
From Los Angeles Times ● Oct. 4, 2026
Now their AI biosecurity startup, called Red Queen Bio, is rushing to design antibodies that can be manufactured to protect against a range of potential pathogens, including the seemingly sci-fi threat of an AI-designed virus.
From The Wall Street Journal ● Sep. 28, 2026
If an AnWj negative person develops antibodies against AnWj and then receives AnWj positive blood, those antibodies can attack the transfused red blood cells.
From Science Daily ● Sep. 19, 2026
In the early 1970s a man named Ted Slavin had done precisely that with antibodies from his blood.
From "The Immortal Life of Henrietta Lacks" by Rebecca Skloot
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.
