in Architecture, a truncated, quadrangular, and slender pyramid, raised as an ornament, and frequently charged with inscriptions or hieroglyphics.

Obelisks appear to have been of very great antiquity, and first raised to transmit to posterity certain precepts, which were cut in hieroglyphical characters; but they were afterwards used to immortalize the great actions of heroes, and the memory of persons who were beloved. The first obelisk mentioned in history was that of Ramesses king of Egypt, which was forty cubits high. Phius, another king of Egypt, raised one of fifty-five cubits; and Ptolemy Philadelphus, another of eighty-eight cubits, in memory of Arsinoe. Augustus erected one at Rome in the Campus Martius, which served to mark the hours on a horizontal dial, drawn upon the pavement. They were called by the Egyptian priests the "fingers of the sun," because they were made in Egypt to serve also as styles or gnomons for marking the hours on the ground. The Arabs still call them "Pharaoh's needles." All the learning on the subject of obelisks will be found accumulated in the elaborate work of Zoega (De Origine et Usu Obeliscorum) printed at Rome, and illustrated with very beautiful and accurate plates, in which the hieroglyphics are represented with great distinctness and accuracy.