Shingon is a Japanese term that refers to a particular sect of Buddhism. In English, there are a few synonyms that can be used to describe this same concept. One option is to simply use the term "Buddhism," as this gives a more general sense of the religion that Shingon is a part of. Another choice is to use the phrase "Esoteric Buddhism," which specifically focuses on the type of practices and beliefs found within Shingon. Additionally, the term "Mikkyo" can be used to describe Shingon, as it is the Japanese term for Esoteric Buddhism. All of these synonyms can be used to convey the same general idea as the term "Shingon".