Septenaries, which refers to a group of seven, has quite a few synonyms. One such synonym is heptad, which is commonly used in scientific contexts. Another synonym is sevenfold, which refers to something that is seven times greater or exists in seven parts. Meanwhile, the term septuple is often used to describe something that is seven times greater or comes in seven parts. Alternatively, you can use the word sevensome, which refers to a group of seven people or objects. Additionally, the word septennium refers to a period of seven years, and septet refers to a musical group composed of seven members.