/sim"i tree/ , n. , pl. symmetries .
1. the correspondence in size, form, and arrangement of parts on opposite sides of a plane, line, or point; regularity of form or arrangement in terms of like, reciprocal, or corresponding parts.
2. the proper or due proportion of the parts of a body or whole to one another with regard to size and form; excellence of proportion.
3. beauty based on or characterized by such excellence of proportion.
4. Math.
a. a geometrical or other regularity that is possessed by a mathematical object and is characterized by the operations that leave the object invariant: A circle has rotational symmetry and reflection symmetry.
b. a rotation or translation of a plane figure that leaves the figure unchanged although its position may be altered.
5. Physics. a property of a physical system that is unaffected by certain mathematical transformations as, for example, the work done by gravity on an object, which is not affected by any change in the position from which the potential energy of the object is measured.
[ 1535-45; symmetria symmetría commensurateness. See SYM-, -METRY ]
Syn. 1. consonance, concord, correspondence. SYMMETRY, BALANCE, PROPORTION, HARMONY are terms used, particularly in the arts, to denote qualities based upon a correspondence or agreement, usually pleasing, among the parts of a whole. SYMMETRY implies either a quantitative equality of parts ( the perfect symmetry of pairs of matched columns ) or a unified system of subordinate parts: the symmetry of a well-ordered musical composition. BALANCE implies equality of parts, often as a means of emphasis: Balance in sentences may emphasize the contrast in ideas.
PROPORTION depends less upon equality of parts than upon that agreement among them that is determined by their relation to a whole: The dimensions of the room gave a feeling of right proportion. HARMONY, a technical term in music, may also suggest the pleasing quality that arises from a just ordering of parts in other forms of artistic composition: harmony of line, color, mass, phrase, ideas.
Ant. 1. asymmetry.