n. [ L. gnomon, Gr. &unr_; one that knows, the index of a sundial. See Gnome. ] [ 1913 Webster ]

1. (Dialing) The style or pin, which by its shadow, shows the hour of the day. It is usually set parallel to the earth's axis. [ 1913 Webster ]

2. (Astron.) A style or column erected perpendicularly to the horizon, formerly used in astronomocal observations. Its principal use was to find the altitude of the sun by measuring the length of its shadow. [ 1913 Webster ]

3. (Geom.) The space included between the boundary lines of two similar parallelograms, the one within the other, with an angle in common; as, the gnomon bcdefg of the parallelograms ac and af. The parallelogram bf is the complement of the parallelogram df. [ 1913 Webster ]

4. The index of the hour circle of a globe.

{ } a. [ L. gnomonicus, Gr. &unr_;: cf. F. gnomonique. See Gnomon. ] Of or pertaining to the gnomon, or the art of dialing. [ 1913 Webster ]

Gnomonic projection, a projection of the circles of the sphere, in which the point of sight is taken at the center of the sphere, and the principal plane is tangent to the surface of the sphere. “The gnomonic projection derives its name from the connection between the methods of describing it and those for the construction of a gnomon or dial.” Cyc. of Arts & Sciences. [ 1913 Webster ]

adv. According to the principles of the gnomonic projection. [ 1913 Webster ]

n. [ See Gnomonic. ] The art or science of dialing, or of constructing dials to show the hour of the day by the shadow of a gnomon. [ 1913 Webster ]

n. One skilled in gnomonics. Boyle. [ 1913 Webster ]

n. [ Gnomon + -logy. Cf. Gnomonology. ] A treatise on gnomonics. [ 1913 Webster ]