A day of the week can also be referred to as a weekday or workday, specifically when talking about the days from Monday to Friday. Additionally, these days can also be called business days, indicating that they are more commonly associated with work and commerce than weekends. The individual days of the week also have unique names, such as Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, and Sunday. These names come from a combination of mythology, religion, and historical reckoning systems. Lastly, less commonly used terms for the days of the week include heptadi and hebdomas, which both refer to the seven-day week cycle.