adjuvant

1 of 2

adjective

ad·​ju·​vant ˈa-jə-vənt 

1

: serving to aid or contribute : auxiliary

2

: enhancing the effectiveness of medical treatment

Retinoids also seem to be useful as adjuvant therapy in the treatment of psoriasis, and they may induce regression of premalignant lesions, including actinic keratoses.

—Robert S. Stern

specifically : of, relating to, or being treatment administered following primary cancer treatment to enhance the outcome of primary treatment

adjuvant chemotherapy following surgery

… women who choose this extensive surgery live no longer than women who choose lumpectomy (with or without adjuvant radiation) and frequent check-ups

—Susan S. Weed

compare neoadjuvant

adjuvant

2 of 2

noun

: one that helps or facilitates: such as

a

: an ingredient (as in a prescription or a solution) that modifies the action of the principal ingredient

b

: something (such as a drug or method) that enhances the effectiveness of medical treatment

used chemotherapy as an adjuvant to surgery

c

: a substance (such as one added to a vaccine) enhancing the immune response to an antigen

Did you know?

Things that are adjuvant rarely get top billing—they're the supporting players, not the stars. But that doesn't mean they're not important. An adjuvant medicine, for example, can have a powerful healing effect when teamed up with another medicine or curative treatment. Adjuvant descends from the Latin verb adjuvare ("to aid"), which also gave English the nouns coadjutor ("assistant") and aid. These days, adjuvant tends to turn up most often in medical contexts, but it can also be used in the general sense of "serving to aid." Likewise, the noun adjuvant can mean "a drug or method that enhances the effectiveness of medical treatment" or simply "one that helps or facilitates."

Examples of adjuvant in a Sentence

Recent Examples on the Web

Adjective

Kennedy has long falsely asserted that vaccines containing aluminum salts as an adjuvant cause health problems. —Joshua P. Cohen, Forbes.com, 1 Aug. 2025

For several months post-surgery, Larry weighed the pros and cons of adjuvant chemotherapy with fluoropyrimidines. —Kerin Milesky, Boston Herald, 26 July 2025

Noun

Vaccines typically comprise two key components: immunogens that trigger an immune response in the body, and adjuvants which boost your immune system's response to the immunogens. —Abhimanyu Ghoshal, New Atlas, 24 June 2025

Aluminum adjuvants are found in vaccines that protect against: These vaccines have all been approved by the U.S. Food and Drug Administration (FDA) after undergoing rigorous evaluation for safety and effectiveness. —Emily Kay Votruba, EverydayHealth.com, 15 July 2025

Word History

Etymology

Adjective

borrowed from Latin adjuvant-, adjuvans, present participle of adjuvāre "to help, aid, facilitate" — more at aid entry 1

Noun

borrowed from Medieval Latin adjuvant-, adjuvans, going back to Latin, present participle of adjuvāre "to help, aid, facilitate" — more at aid entry 1

First Known Use

Adjective

1574, in the meaning defined at sense 1

Noun

1583, in the meaning defined above

Rhymes for adjuvant

• movant
• neoadjuvant

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Medical Definition

adjuvant

1 of 2 adjective

ad·​ju·​vant ˈaj-ə-vənt 

1

: serving to aid or contribute

2

: assisting in the prevention, amelioration, or cure of disease

adjuvant chemotherapy following surgery

adjuvant

2 of 2 noun

: one that helps or facilitates: as

a

: an ingredient (as in a prescription or solution) that facilitates or modifies the action of the principal ingredient

the beneficial activity of the spray is enhanced by adjuvants

b

: something (as a drug or method) that enhances the effectiveness of a medical treatment

used chemotherapy as an adjuvant to surgery

c

: a substance enhancing the immune response to an antigen