Principally used in Classical architecture, the lowest of the three main parts of an entablature that rests on the abacus of a column, comprising a horizontal beam that spans the columns or piers in the manner of a lintel. The other two parts of the entablature are the cornice and the frieze. For the architrave-like molded frame that surrounds a door or window, use "architrave trim." For the ornamental moldings around the exterior curve of an arch, use "archivolts."