What term describes the balanced distribution and arrangement of forms and spaces on opposite sides of a center axis?

The term that best describes the balanced distribution and arrangement of forms and spaces on opposite sides of a center axis is symmetry. Symmetry is a foundational principle in architectural design, where elements are mirrored along a central line or point, creating visual harmony and balance. This concept can be seen in various architectural styles and structures, where the careful arrangement of windows, doors, and other features creates a cohesive and aesthetically pleasing appearance.

In contrast to symmetry, the other terms focus on different aspects of design. For example, 'axis' refers to an imaginary line that serves as a reference point around which elements are arranged but does not inherently indicate balance. 'Hierarchy' involves the arrangement of elements in a way that signifies importance, leading to a sense of order but not necessarily balance around an axis. Lastly, 'transformation' pertains to changes in shape or form without implying balance or arrangement. Thus, symmetry is the term that accurately captures the notion of balanced distribution on either side of a center axis in architectural design.