Semitonic is a word that describes anything related to a half step in music theory. There are a few different synonyms that can be used in place of this word. One of the most common is chromatic, which refers to the use of half-steps in music. Another synonymous term is diatonic, which describes a system of pitches arranged according to a specific pattern of whole and half steps. Finally, there is enharmonic, which refers to notes that are written differently but sound the same (such as C# and Db). All of these terms are closely related to the concept of semitones, and can be used interchangeably in most contexts.