Being adjunct refers to a subordinate or secondary role or position. Some possible antonyms for being adjunct could be "leading," "primary," or "central." These words suggest prominence or dominance, and indicate a powerful or influential role. Another possible antonym could be "independent," which suggests freedom from the control or influence of others. Other potential antonyms for being adjunct might include "integral," "crucial," or "essential," indicating the importance or necessity of a particular role or position. Ultimately, the choice of antonym will depend on the context in which the word is used and the specific connotations that are desired.