A __________ is a four sided figure with all four sides of equal length and all angles right angles.

A square is defined as a four-sided figure, or quadrilateral, where all four sides are of equal length and all angles measure 90 degrees, making them right angles. This specific set of properties distinguishes a square from other quadrilaterals.

In contrast, a rhombus also has four sides of equal length, but its angles are not necessarily right angles; they can vary. A rectangle, on the other hand, has all angles as right angles and opposite sides that are equal in length, but not all four sides are equal. A trapezoid, meanwhile, is defined as having at least one pair of parallel sides, and its sides and angles can vary significantly, not conforming to the equal-length and right-angle conditions of a square.

Therefore, the properties of a square uniquely satisfy the condition set forth in the question, making it the correct answer.