adjuvant
1. [ adjective ] (pharmacology) enhancing the action of a medical treatment
Examples:

"the adjuvant action of certain bacteria"

Related terms: pharmacology helpful
2. [ adjective ] relating to something that is added but is not essential
Synonyms: adjunct ancillary appurtenant auxiliary subsidiary accessory
Examples:

"an ancillary pump" "an adjuvant discipline to forms of mysticism" "The mind and emotions are auxilliary to each other"

Related terms: supportive
3. [ noun ] an additive that enhances the effectiveness of medical treatment
Related terms: additive