"auxiliary" in the noun sense

1. aide, auxiliary

someone who acts as assistant

"auxiliary" in the adjective sense

1. auxiliary, subsidiary, supplemental, supplementary

functioning in a supporting capacity

"the main library and its auxiliary branches"

2. accessory, adjunct, ancillary, adjuvant, appurtenant, auxiliary

furnishing added support

"an ancillary pump"

"an adjuvant discipline to forms of mysticism"

"The mind and emotions are auxiliary to each other"

Source: WordNet® (An amazing lexical database of English)

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