Noun
axis of symmetry (plural axes of symmetry)
(geometry) Any of one or more lines about which a geometric figure is symmetric
Alternative definitions are a quadrilateral with an axis of symmetry bisecting one pair of opposite sides, or a trapezoid with diagonals of equal length. Source: Internet
An "axis of anisotropy" is defined as the axis along which isotropy is broken (or an axis of symmetry, such as normal to crystalline layers). Source: Internet
For a generic solid object without any axis of symmetry, the evolution of the object's orientation, represented (for example) by a rotation matrix R that transforms internal to external coordinates, may be numerically simulated. Source: Internet
Corollary concerning midpoints and endpoints of chords A corollary of the above discussion is that if a parabola has several parallel chords, their midpoints all lie on a line which is parallel to the axis of symmetry. Source: Internet
Deductions Measured along the axis of symmetry, the vertex, A, is equidistant from the focus, F, and from the directrix. Source: Internet
It is not restricted to the situation where the axis of symmetry is parallel to the y-axis. Source: Internet