Hebdomads is a word that refers to a group of seven things. However, there are many synonyms that can be used instead depending on the context. For example, in the field of astronomy, the word "week" is often used. In medicine, seven-day cycles are referred to as "septenary periods." The word "week-long" is also commonly used to describe a period of seven days. In religion, the term "seven-day period" is used, and in mathematics, the word "heptad" is often used to describe a group of seven different items or concepts. Regardless of the context, there are many synonyms available to describe a collection of seven things.