From the info I’m gathering, a parallelogram and rhomboid are the same thing. A rhomBUS is different. A rhomboid is two sets of parallel lines but not all four sides have to be equal. Just the opposing lines. But that the same for a parallelogram. For a rhombus, all four sides are equal in length. I remember learning in eighth grade about the definitions of a trapezoid (a figure with at least one set of parallel lines), a parallelogram with two sets of parallel lines (making it also a trapazoid since it does fit the description), a rhombus (a figure with two sets of parallel lines all of equal length, making it also a trapezoid and a parallelogram), a rectangle (a figure with two sets of parallel lines and the opposing lines are equal in length forming four right angles, making it also a trapezoid, a parallelogram). Finally, a square is really special. It’s definition is a figure of two pairs of parallel lines, all of equal length, forming four right angles. This definition includes the definitions of all the others. A square is a trapezoid because it has AT LEAST one set of parallel lines. It’s a parallelogram because it has two sets of parallel lines and opposing sides are equal. It’s a rhombus because the four sides are equal in length and parallel to each other. And it’s a rectangle because the sides form four right angles and opposite parallel sides are equal in length! I love squares!