What is a four sided figure where all sides are equal in length, but angles are not right angles?

The figure described is a rhombus, which is defined as a four-sided polygon (quadrilateral) where all sides are equal in length. Unlike a square, which has the additional property of having right angles at each vertex, a rhombus does not require its angles to be right angles; they can vary in size. This characteristic is crucial in distinguishing a rhombus from other quadrilaterals.

In contrast, a square must have all four sides equal and all four angles right angles, which does not fit the given description. A rectangle, while having equal opposite sides and right angles, fails to meet the criteria of equal side lengths. A rhomboid has pairs of equal opposite sides and angles that are not necessarily right angles, but it does not require all four sides to be equal, which is essential to classify a figure as a rhombus.

Thus, the unique properties of a rhombus align perfectly with the question's criteria, making it the correct choice.