Definify.com
Webster 1913 Edition
Gnomon
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.
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.
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
. The parallelogram bf is the complement of the parallelogram df. gnomon
bcdefg of the parallelograms ac and af
Webster 1828 Edition
Gnomon
GNO'MON
,Noun.
1.
In dialling, the style or pin, which by its shadow shows the hour of the day. It represents the axis of the earth.2.
In astronomy, a style erected perpendicular to the horizon, in order to find the altitude of the sun.3.
The gnomon of a globe, is the index of the hour-circle.