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

Thanks to research and testing at Tulane University, a new adjuvant vaccine development could eradicate whooping cough, much like smallpox. —Craig Shoup, The Tennessean, 27 Nov. 2024

Chemotherapy Chemotherapy is one of the most common forms of adjuvant therapy. —Ruth Jessen Hickman, Health, 20 Sep. 2024

Noun

Other active placebos in the studies in Scott’s project included shots that contained only an adjuvant, an ingredient that’s added to vaccines to trigger a stronger immune response. —Brenda Goodman, CNN Money, 5 June 2025

Some nasal vaccines use adjuvants to overcome tolerance, but in the nose, adjuvants can pose unique dangers. —Stephani Sutherland, Scientific American, 15 Oct. 2024

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