BASE, in geometry, the lowest side of the perimeter of a figure: Thus, the base of a triangle may be said of any of its sides, but more properly of the lowest, or that which is parallel to the horizon. In rectangled triangles, the base is properly that side opposite to the right angle.
Base of a Solid Figure, the lowest side, or that on which it stands.
Base of a Conic Section, a right line in the hyperbola and parabola, arising from the common intersection of the secant plane and the base of the cone.