A rhombus is a parallelogram (four-sided polygon where opposite sides are parallel) with all sides equal in length. A rhombus with all angles equal is called a square. A rhombus is usually tilted on its side. It comes from the Greek word rhombos, meaning "spinning top".
- "Online Etymology Dictionary". etymonline.com. http://www.etymonline.com/index.php?search=rhombus&searchmode=none. Retrieved 10 January 2011.