a. [ Cf. F. symétrique. See Symmetry. ] 1. Involving or exhibiting symmetry; proportional in parts; having its parts in due proportion as to dimensions; as, a symmetrical body or building. [ 1913 Webster ] 2. (Biol.) Having the organs or parts of one side corresponding with those of the other; having the parts in two or more series of organs the same in number; exhibiting a symmetry. See Symmetry, 2. [ 1913 Webster ] 3. (Bot.) (a) Having an equal number of parts in the successive circles of floral organs; -- said of flowers. (b) Having a likeness in the form and size of floral organs of the same kind; regular. [ 1913 Webster ] 4. (Math.) Having a common measure; commensurable. (b) Having corresponding parts or relations. [ 1913 Webster ] ☞ 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, so situated that the line joining the two corresponding points is perpendicular to the line or plane and is bisected by 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 letters a, b, c. [ 1913 Webster ] -- Sym*met"ric*al*ly, adv. -- Sym*met"ric*al*ness, n. [ 1913 Webster ] | 