in geometry, a solid standing on a trian- Pyramid, triangular, square, or polygonal basis, and terminating in a point at the top; or, according to Euclid, it is a solid figure consisting of several triangles, whose bases are all in the same plane and have one common vertex.

Pyramids are sometimes used to preserve the memory of singular events; and sometimes to transmit to posterity the glory and magnificence of princes. But as they are esteemed a symbol of immortality, they are most commonly used as funeral monuments. Such is that of Cælius at Rome; and those other celebrated ones of Egypt, as famous for the enormity of their size as their antiquity. These are situated on the west side of the Nile, almost opposite to Grand Cairo: the base of the largest covers more than 10 acres of ground; and is, according to some, near 700 feet high, though others make it 600, and some but little more than 500. The pyramid is said to have been, among the Egyptians, a symbol of human life; the beginning of which is represented by the base, and the end by the apex; on which account it was, that they used to erect them over sepulchres. See Egypt, no. 10.