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.

Altern Base. See Altern.

Base, in architecture, is used for any body which bears another, but particularly for the lower part of a column and pedestal. See Architecture.

Base, in fortification, the exterior side of the polygon, or that imaginary line which is drawn from the flanked angle of a bastion, to the angle opposite to it.

Base, in gunnery, the least part of ordnance, the diameter of whose bore is \(1\frac{1}{4}\) inch, weight 200 pound, length 4 feet, load 5 pound, shot 1\(\frac{1}{2}\) pound wt. and diameter 1\(\frac{1}{2}\) inch.

Base line, in perspective, the common section of a picture, and the geometrical plane.

Distinct Base, in optics. See Focus.

Base of the heart, in anatomy, denotes its upper part.

Base, or Bass, in music. See Bass.

Base point, in heraldry. See Point.