The phrase "be adjacent to" implies a sense of proximity and bordering relationship. The antonym for this phrase would be "be distant from" or "be far away from," suggesting separation and distance rather than nearness. Other antonyms for "be adjacent to" include "be disconnected from," "be detached from," or "be disengaged from." These antonyms indicate a lack of connection or relationship between two objects or spaces. Another antonym could be "be perpendicular to," suggesting a relationship that is at right angles rather than parallel. Ultimately, the choice of antonym depends on the context and the specific relationship between the two objects.