When it comes to expressing the idea of a "predominant part," there are a plethora of synonyms available. One could use terms like "dominant section," "primary component," and "majority section" to highlight the most important part of something. Other synonyms that could be employed include "prevalent piece," "leading element," "dominant portion," and "key segment." The term "prominent element" is another useful synonym, as it implies that a specific part is noticeable or outstanding in some way. Ultimately, using any of these synonyms for "predominant part" could help to convey a sense of importance and emphasis on a specific aspect of a topic or object.