In geometry, a rhombus or rhomb's a quadrilateral whose four sides all have the same length. The rhombus's often called a diamond, after the diamonds suit in playing cards, or a lozenge, though the latter sometimes refers specifically to a rhombus with a 45° angle. In general, a polygon whose sides have the same length's called equilateral, so a rhombus's an equilateral quadrilateral. Every rhombus's a parallelogram, and a rhombus with right angles's a square. (Euclid's original definition o… (More on Rhombic)