Equidistant

The apothem of a regular polygon is the distance from the center of the polygon to a side, and is equidistant to all sides of the polygon.

The Miquel point of a quadrilateral is the point where the circumcircles of the four triangles formed by its diagonals intersect, and is equidistant from the four vertices.

The distance between a point and a line is the length of the perpendicular segment that connects the point to the line at the equidistant point.

The center of a hyperbola is the point that is equidistant from the two foci of the hyperbola.

An isosceles trapezoid can also be an equidistant polygon.