Sym-mĕt'rie-al, a.
a. [Fr. symétrique, It. simmetrico, Sp. simetrico.]
Sense 1. Involving or exhibiting symmetry; proportional in its parts; having its parts in due proportion as to dimensions; as, a symmetrical body or building.
Sense 2. (Bot.) Having an equal number of parts of each sort, or in each set or circle of organs, as five sepals, five petals, and five stamens. Gray.
Sense 3. (Math.) Having corresponding parts or relations.
☞ A curve or a plane figure is symmetrical with respect to a given line, and a line, surface, or solid with respect to a plane, when for each point on one side of the line or plane there is a corresponding point on the other side, similarly situated, and equally distant from it. Two solids are symmetrical when they are so situated with respect to an intervening plane that the several points of their surfaces thus correspond to each other in position and distance. In analysis, an expression is symmetrical with respect to several letters when any two of them may change places without affecting the expression; as, the expression a²b + ab² + a²c + ac² + b²c + bc², is symmetrical with respect to the three letters a, b, c.