The term "aide-de-camp" refers to a military officer who acts as an assistant to a higher-ranking officer. Antonyms for aide-de-camp could include "enemy," "opponent," or "adversary," as these individuals would be in direct opposition to the higher-ranking officer being assisted. Other possible antonyms might include "traitor" or "defector," indicating someone who has betrayed their own side, causing harm to the officer they were meant to serve. Alternatively, the word "lone wolf" could be seen as an antonym for aide-de-camp, as it conjures an image of someone working independently rather than as part of a team.