What does the term "symmetrical" describe in a physical context?

The term "symmetrical" in a physical context refers to the concept of having exact parts that are facing each other or arranged around a central axis. This means that if you were to draw a line through the center of a symmetrical object, the two halves would mirror each other perfectly. For example, if you look at a butterfly, the wings on either side of the body are symmetrical in that they are mirror images.

This is fundamental in various fields, including art, architecture, and biology, as symmetry often conveys a sense of balance and harmony. In contrast, the other options do not capture the essence of symmetry: the complete absence of shape suggests formlessness, a random arrangement lacks any order or mirroring, and having only one side distinct means there isn't a symmetry to be found between two halves or sides.