(Lat. *cuspis*, a spear-point). In astronomy, the points or horns of the moon, or of any other luminary, are termed cusps. In architecture, cusp is used to denote the points of the small arcs or foliations terminating the internal curves of trefoiled, cinquefoiled, &c. heads of Gothic windows and panels. Cusp, in astrology, denotes the first point of each of the twelve houses, in a figure or scheme of the heavens.