I. ˈsimə.trē, -ri noun
( -es )
Etymology: Latin symmetria, from Greek, commensurability, proportion, symmetry, from symmetros commensurate, suitable, symmetrical (from syn- + metron measure) + -ia -y — more at measure
1.
a. obsolete : mutual relationship of parts (as in size, arrangement, or measurements) : proportion
b. : due or balanced proportions : beauty of form or arrangement arising from balanced proportions
with order, symmetry , and taste unblest — Robert Burns
2. : correspondence in size, shape, and relative position of parts that are on opposite sides of a dividing line or median plane or that are distributed about a center or axis : an arrangement or external form (as in a body, a design, or a grouping) marked by bilateral conformity or geometrical regularity — see bilateral symmetry , radial symmetry
3. : the property of being symmetrical
4. : the property of a crystal of having two or more directions that are alike in physical and crystallographic respects because of identity of atomic structure in the directions concerned or mirror-image relations along such directions
II. noun
1. : a rigid motion of a geometric figure that determines a one-to-one mapping onto itself
2. : interchangeability of particles and equivalence of interactions existing between forces of nature at very high energies
3. : 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