Gnomon

2 definitions found

From The Collaborative International Dictionary of English v.0.48 [gcide]:

  Gnomon \Gno"mon\, n. [L. gnomon, Gr. ? 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. Gnomonic

From WordNet (r) 2.0 [wn]:

  gnomon
       n : indicator provided by the stationary arm whose shadow
           indicates the time on the sundial