The word "most fractured" implies a state of being severely broken or fragmented. Some antonyms for this phrase could include "solid," "intact," or "unbroken." These words suggest a sense of wholeness, stability, and durability. Other antonyms might include "unfragmented," "unscathed," or "unimpaired," all of which imply a lack of damage or injury. These contrasting terms may be useful in describing the state of objects or structures, such as bones, rocks, or buildings. Regardless of the context, however, the antonyms for "most fractured" all share a common theme of completeness and coherence.