Any equilibrium in which opposite changes occur simultaneously. / (chemistry) An equilibrium in which two reversible reactions occur at the same rate.

(mathematics) a set of equations that defines the coordinates of the dependent variables (x, y and z) of a curve or surface in terms of one or more independent variables or parameters

(mathematics) An equation involving a function f(x) and integrals of that function to be solved for f(x)

(astronomy, celestial mechanics) the mathematical relationship between the mean anomaly (M) and the eccentric anomaly (E) of a planet in an elliptical orbit with eccentricity (𝜀). M=E-𝜀· sin (E).

(geometry, of a polygon) Having all the sides equal. / (geometry, of a polyhedron) Having all the faces equal.

A side exactly corresponding, or equal, to others. / A figure having all its sides equal.

(geometry) Of a polygon, having all interior angles equal. This is not necessarily a regular polygon, since that would also be equilateral; a rectangle is equiangular but not equilateral, unless it is a square.

(chemistry) An equation which approximates the dependence of the rate of any chemical reaction on the temperature.

(cartography) Of a map, having the property that equal areas on the map represent equal areas on the mapped surface.

(physics) A partial differential equation which describes the conservation of linear momentum for a Newtonian incompressible fluid.