a line about which a symmetrical three-dimensional object can be rotated so that its turn image matches its original position more than once in a full turn

a fake line that goes through the middle of the crystal

a line with respect to which a body can be symmetrical

a line withrespect to which a body can be symmetrical

dashed vertical line that contains the vertex

A line associated with a geometric figure such that every point on one side of the line has a corresponding point on the other side.

A line dividing an area into two parts equal and similar to each other, and similarly disposed to the line.

An axis of symmetry is a line about which something is symmetrical. For example, the diameter of a circle is an axis of symmetry.+, - EnchantedLearning.com Math Dictionary

An axis of symmetry (also called a rotational axis) is an imaginary line around which an object can be rotated a certain number of degrees and look like the original shape. When two planes of symmetry intersect, they form a straight line, which is an axis of symmetry. See more in the entry on crystal systems

A line dividing an area into two similar but opposite handed figures.

(also called a rotational axis). An imaginary line around which an object can be rotated a certain number of degrees and still resemble the original shape. When two planes of symmetry intersect, they form a straight line, which is the axis of symmetry. Symmetry is one of the factors jewelers look for when grading cut stones. See Four C's.