The part of a sundial that casts a shadow. It may consist of a rod or a raised surface, as in designs where the edge of a decoration casts the shadow. If the gnomon is a triangular plate, the shadow-casting edge is known as the style.
Geology and Earth Sciences
A device that is erected beside a rock or structure of interest to provide a reference for the vertical and colour. It was used during the manned exploration of the Moon.