By much is a phrase used to describe something that happens or exists to a large degree. There are several synonyms for this phrase that can be used depending on the context of the sentence. One such synonym is 'by far', which is often used to describe a significant difference between two things. Another synonym for by much is 'by a large margin', which also expresses a substantial difference or advantage of one thing over another. 'Considerably' is another synonym and indicates a significant amount or extent of something, while 'greatly' is a synonym that expresses a large degree or intensity of something. Other synonyms for the phrase include 'vastly' and 'significantly'.