Antonyms for the phrase "all that" include "none of that," "nothing," or "not everything." These antonyms have the opposite meaning of the original phrase, which denotes a sense of completeness, wholeness, or satisfaction. When something is identified as "all that," it is often regarded as exceptional, superior, or outstanding. However, the antonyms suggest an absence or lack of something, which may indicate mediocrity, inadequacy, or unremarkable qualities. Therefore, the appropriate antonym to use depends on the context and the intended meaning. Nonetheless, antonyms provide an effective way to express the opposite of a word, thereby enhancing clarity and precision in communication.