A significant anniversary is often referred to as a JUBILEE. It is a celebration of an event that has occurred in the past, usually one that has been significant in some way. Jubilees are typically celebrated with special events and ceremonies, and can be held for any number of years, from 10 to 100 or more. They are often used to mark important milestones in a person's life, such as a wedding anniversary, or to commemorate a major event in history.