Sum and substance, a phrase often used to convey the essence or main point of something, can be replaced by a variety of synonyms. Some examples include crux, gist, core, essence, heart, kernel, marrow, pith, and quintessence. Each of these words carries the same meaning as sum and substance, emphasizing the most important and relevant details of a topic or situation. Choosing the right synonym for sum and substance can help to convey your message more clearly and effectively, allowing you to communicate your ideas and opinions with greater precision and impact.