Metathetic is a word used to describe a phonetic phenomenon where sounds in a word are rearranged. Synonyms for metathetic include transpositional, anaptyctic, and antithetical. Transpositional denotes a change in position or arrangement of elements in a word, while anaptyctic is used to describe the insertion of a sound or letter into a word. Antithetical, on the other hand, refers to two things that are completely opposite. Other synonyms for metathetic include invertible, transformable, and transposable. These words all describe a concept where something can be changed or shifted in some way, whether it be through phonetics or otherwise.