Base is a term usually applied to the lowest part of any thing; thus, in Geometry, it is the lowest side of the perimeter of a figure; in Architecture, the lowest part of a column, or pedestal; in Building, the lowest apartment is also called the basement.

BASE, in Surveying, is a line measured with the greatest exactness, on which a series of triangles are constructed, in order to determine the position of objects and places.

Base, In Chemistry

Any body which is dissolved by another body, which it receives and fixes, and with which it forms a compound, may be called the base of that compound. Thus, for example, the base of neutral salts, are the alkaline, earthy, and metallic matters, which are saturated by the several acids, and form, with them, these neutral salts.