[sym.me.try] n, pl -tries [L symmetria, fr. Gk, fr. symmetros symmetrical, fr. syn- + metron measure--more at measure] (1541) 1: balanced proportions; also: beauty of form arising from balanced proportions
2: the property of being symmetrical; esp: correspondence in size, shape, and relative position of parts on opposite sides of a dividing line or median plane or about a center or axis--compare bilateral symmetry, radial symmetry
3: a rigid motion of a geometric figure that determines a one-to-one mapping onto itself
4: the property of remaining invariant under certain changes (as of orientation in space, of the sign of the electric charge, of parity, or of the direction of time flow)--used of physical phenomena and of equations describing them