E·qui·lat·er·al a.  Having all the sides equal; as, an equilateral triangle; an equilateral polygon.
 Equilateral hyperbola Geom., one whose axes are equal.
 Equilateral shell Zoöl., one in which a transverse line drawn through the apex of the umbo bisects the valve, or divides it into two equal and symmetrical parts.
 Mutually equilateral, applied to two figures, when every side of the one has its equal among the sides of the other.