adjective

- characterized by or exhibiting symmetry; well-proportioned, as a body or whole; regular in form or arrangement of corresponding parts.
- Geometry.
- noting two points in a plane such that the line segment joining the points is bisected by an axis: Points (1, 1) and (1, −1) are symmetrical with respect to the x-axis.
- noting a set consisting of pairs of points having this relation with respect to the same axis.
- noting two points in a plane such that the line segment joining the points is bisected by a point or center: The points (1, 1) and (−1, −1) are symmetrical with respect to (0, 0).
- noting a set consisting of pairs of points having this relation with respect to the same center.

- Often symmetric. Mathematics.
- noting a square matrix that is equal to its transpose.
- noting a dyad or dyadic that is equal to its conjugate.
- noting a relation in which one element in relation to a second implies the second in relation to the first.

- Botany.
- divisible into two similar parts by more than one plane passing through the center; actinomorphic.
- (of a flower) having the same number of parts in each whorl.

- Chemistry.
- having a structure that exhibits a regular repeated pattern of the component parts.
- noting a benzene derivative in which three substitutions have occurred at alternate carbon atoms.

- affecting corresponding parts simultaneously, as certain diseases.

adjective

- possessing or displaying symmetryCompare asymmetric
- maths
- (of two points) capable of being joined by a line that is bisected by a given point or bisected perpendicularly by a given line or planethe points ( x, y ) and ( –x, –y ) are symmetrical about the origin
- (of a configuration) having pairs of points that are symmetrical about a given point, line, or planea circle is symmetrical about a diameter
- (of an equation or function of two or more variables) remaining unchanged in form after an interchange of two variablesx + y = z is a symmetrical equation

- chem (of a compound) having a molecular structure in which substituents are symmetrical about the molecule
- botany another word for isomerous
- Also: symmetric (of a disease, infection, etc) affecting both sides of the body or corresponding parts, such as both legs

adj.1570s (implied in symmetrically), from symmetry + -ical.