A calendar is a system for naming periods of time, typically days. These names are known as calendar dates. Cycles in a calendar are often synchronised with the perceived motion of astronomical objects. A calendar is also a physical device (often paper). This is the most common usage of the word. As a subset, 'calendar' is also used to denote a list of particular set of planned events (for example, court calendar). A full calendar system has a different calendar date for every day. Thus the week cycle is by itself not a full calendar system...