a trapezoid that is NOT isosceles
A quadrilateral. It may be a rectangle, parallelogram, trapezoid, or an irregular quadrilateral.
always
sometimes
A rhombus.
trapezoid
A general quadrilateral has no equal sides, but it also has no specific name. Among quadrilaterals with a name, a trapezium (unless it is isosceles) can have no equal sides.
square
It is a rectangle
There is no specific name for such a quadrilateral.
All quadrilaterals have two [pairs] of opposite sides and in most cases they are not equal.
Many different types of quadrilaterals can have three equal side lengths. as long as it is a closed shape that has four sides, it is considered a quadrilateral, but not all quadrilaterals have names. A triangle with three equal side length would be called an equilateral triangle.
A quadrilateral is not necessarily a rhombus; rather, a rhombus is a specific type of quadrilateral. All rhombuses are quadrilaterals, but not all quadrilaterals are rhombuses. A rhombus is defined by having all four sides of equal length and opposite angles that are equal. In contrast, a quadrilateral can have varying side lengths and angles.