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Definitions

adjuvant

[aj-uh-vuhnt] / ˈædʒ ə vənt /
ADJECTIVE
ancillary
Synonyms
STRONGEST
additional
WEAK
accessory accompanying appurtenant attendant attending coincident collateral concomitant contributory incident satellite secondary subordinate subservient subsidiary
Antonyms
WEAK
necessary needed
ADJECTIVE
auxiliary
Synonyms
STRONGEST
ancillary
STRONG
accessory backup complementary extra reserve secondary spare subordinate subsidiary supporting
WEAK
abetting appurtenant contributory subservient
Antonyms
STRONG
chief important necessary superior
WEAK
body main
ADJECTIVE
collateral
Synonyms
STRONGEST
ancillary
STRONG
accessory attendant auxiliary complementary concomitant coordinate dependent incident lateral parallel roundabout satellite side sub subordinate subsidiary supporting tributary
WEAK
accompanying added adjunctive appurtenant circuitous coincident concurrent confirmatory corresponding corroborative not lineal related subservient under
Antonyms
STRONG
chief different dissimilar important independent major necessary unrelated
WEAK
direct main primary principal
ADJECTIVE
concomitant
Synonyms
STRONG
accessory attendant attending belonging coefficient coeval collateral complementary contemporary coordinate corollary fellow incident joint satellite
WEAK
agreeing ancillary associated with associative coetaneous coexistent coincident coincidental concordant concurrent conjoined conjoined with connected contemporaneous coterminous coupled with in tempo in time isochronal isochronous synchronal synchronous synergetic synergistic
Antonyms
WEAK
accidental chance unrelated
ADJECTIVE
subordinate
Synonyms
STRONG
accessory auxiliary collateral dependent inferior junior low lower minor satellite secondary sub subaltern subject subnormal subsidiary tributary
WEAK
ancillary baser below par contributory insignificant paltry second-fiddle second-string smaller subalternate submissive subservient substract under underaverage unequal
Antonyms
STRONG
chief first-class first-rate important main primary source strong superior
WEAK
major necessary vital
ADJECTIVE
subservient
Synonyms
STRONGEST
inferior
WEAK
accessory ancillary appurtenant auxiliary bush-league collateral conducive contributory helpful instrumental minor serviceable subordinate subsidiary supplemental supplementary
Antonyms
WEAK
controlling domineering unhelpful unnecessary useless
ADJECTIVE
subsidiary
Synonyms
STRONGEST
ancillary supplementary
STRONG
accessory assistant auxiliary backup branch collateral cooperative minor subject subordinate
WEAK
aiding appurtenant assisting contributory lesser serviceable subservient supplemental tributory useful
Antonyms
STRONG
chief main major
WEAK
important necessary
ADJECTIVE
supportive
Synonyms
WEAK
abetting accessory ancillary appurtenant assistant backup collateral complementary contributory extra reserve secondary spare subordinate subservient subsidiary supporting
NOUN
catalyst
Synonyms
STRONGEST
impetus incentive motivation stimulant
STRONG
agitator enzyme goad impulse incendiary incitation incitement reactant reactionary spur synergist
WEAK
radical stimulus spark plug wave maker
Antonyms
STRONGEST
block hindrance
WEAK
blockage preventer prevention
NOUN
leavening
Synonyms
STRONG
agitator enzyme ferment goad impetus impulse incendiary incentive incitation incitement leaven motivation reactant reactionary spur stimulant synergist yeast
WEAK
radical stimulus spark plug wave maker
Antonyms
STRONG
block discouragement hindrance

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

The adjuvant is a substance that activates the immune system to recognize the antigen, treat it as a foreign intruder and eliminate it.

From Science Daily • Oct. 13, 2025

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 study found that the adjuvant encouraged a mucosal immune response, spurring the activation of immune cells in the respiratory tract critical for halting the bacteria's ability to colonize.

From Science Daily • Nov. 18, 2024

Adj. aiding &c. v.; auxiliary, adjuvant, helpful; coadjuvant &c.

From Roget's Thesaurus of English Words and Phrases by Roget, Peter Mark