Antonyms for the phrase "in high spirits" include adjectives like dejected, despondent, disheartened, and melancholy. These words express a sense of downheartedness or sadness, conveying a negative emotional state that stands in stark contrast to being in high spirits. If someone is feeling dejected, for example, they may lack energy and enthusiasm, while a person who is melancholy might feel a sense of profound sadness or despair. While in high spirits suggests positivity, enthusiasm, and optimism, these antonyms undoubtedly imply the opposite, indicating a less buoyant emotional state.