The term cornice comes from Italian cornice, meaning "ledge." In French: "corniche" and German: "Gesims."
Cornice molding is generally any horizontal decorative molding which crowns any building or furniture element: the cornice over a door or window, for instance, or the cornice around the edge of a pedestal. A simple cornice may be formed just with a crown molding.
The function of the projecting cornice is to throw rainwater free of the building's walls. In residential building practice, this function is handled by projecting gable ends, roof eaves, and gutters. The elimination of the cornice has been important enough in modernist architecture, often simply for demands of style, that elaborate internal drainage systems are provided.

Classical architecture

Main article: Geison Horizontal geison
In the Doric order, the sloped underside of the horizontal geison is decorated with a series of protruding, rectangular mutules aligned with the triglyphs and metopes of the Doric frieze below. Each mutule typically had three rows of six guttae (decorative conical projections) protruding from its underside. The gaps between the mutules are termed viae (roads). The effect of this decoration was to thematically link the entire Doric entablature (architrave, frieze, and geisa) with a repeating pattern of vertically and horizontally aligned architectural elements. Use of the hawksbill molding at the top of the projecting segment is common, as is the undercutting of the lower edge to aid in dispersing rainwater. In order to separate the geison from the frieze visually, there is typically a bed molding aligned with the face of the triglyphs.

Ionic and Corinthian orders
A raking geison ran along the top edge of a pediment, on a temple or other structure such as the aedicula of a scaenae frons (theater stage building). This element was typically less decorative than the horizontal geison, and often of a differing profile from the horizontal geison of the same structure. The difference is particularly marked in the Doric order, where the raking geison lacks the distinctive mutules. The raking sima ran over the raking geison as a decorative finish and, essentially, a rain gutter.