adjuvant
Americanadjective
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serving to help or assist; auxiliary.
You'll be serving in an adjuvant capacity, on call if we need you.
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Medicine/Medical. utilizing drugs, radiation therapy, or other means of supplemental treatment following cancer surgery or other primary cancer treatment.
The cancer was caught at such an early stage that adjuvant measures were determined to be unnecessary.
noun
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a person or thing that aids or helps.
a team of adjuvants.
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Medicine/Medical, Pharmacology. anything that aids in the treatment of disease, management of pain, etc., especially a substance added to a medication to aid the effect of the main ingredient.
For some in acute pain, caffeine is an effective analgesic adjuvant.
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Immunology. a substance admixed with an immunogen in order to elicit a more marked immune response.
Aluminum salts have been used as adjuvants in vaccines for many decades.
adjective
noun
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something that aids or assists; auxiliary
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med a drug or other substance that enhances the activity of another
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immunol a substance that enhances the immune response stimulated by an antigen when injected with the antigen
Etymology
Origin of adjuvant
First recorded in 1570–80; from Latin adjuvant- (stem of adjuvāns, adjective use of present participle of adjuvāre ), equivalent to prefix ad- + juv- (stem of juvāre “to help”) + -ant; ad- ( def. ), aid, -ant
Explanation
An adjuvant is something added to help boost effectiveness or facilitate a process. For example, in a vaccine, certain adjuvants help create a stronger and longer-lasting immune response to an antigen. In medicine, adjuvants can be anything used to enhance the effectiveness or manageability of treatments, including things like pain medicines, or substances that protect healthy tissue when undergoing chemotherapy treatments. The word adjuvant is also used outside of medicine to name or describe anything or anyone that helps: An adjuvant added to a fungicide doesn't kill a fungus, but it helps the fungicide work better. A good study guide could be an adjuvant in preparing for a big test. Adjuvant comes from the Latin adjuvare, meaning "to help."
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.
Nevertheless, negative results for breast cancer drug candidate giredestrant as a first-line treatment mean the majority of its opportunity is in the so-called adjuvant setting, when drugs are given after tumor-removal surgery, the analysts add.
From The Wall Street Journal • Mar. 12, 2026
We did look at developing an mRNA vaccine for rhinoviruses, but in the end, we decided to go with a protein vaccine with an adjuvant.
From Slate • Oct. 8, 2025
The new vaccine combines the traditional pertussis antigens with an innovative adjuvant called T-vant, which boosts the body's immune response specifically in the respiratory tract.
From Science Daily • Nov. 18, 2024
It’s the princess’ first official engagement since she concluded adjuvant chemotherapy for an undisclosed form of cancer.
From Los Angeles Times • Sep. 18, 2024
Voss adopts almost the words of Quintilian, "Manus non modo loquentem adjuvant, sed ipsæ pene loqui videntur," while Cresollius calls the hand "the minister of reason and wisdom ... without it there is no eloquence."
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.
