Definition of graticule:
(n) :
(geography) The network of lines of latitude and longitude that make up a coordinate system such as the one used for charts and maps of the Earth.
(n) :
A grid of horizontal and vertical lines; specifically, one used as a guide to proportionately enlarge or reduce a drawing.
(n) :
(UK, optics) Synonym of reticle (“a transparent plate marked with a crosshair, grid, or scale which is used in an optical instrument, etc., to aid in alignment, counting, or measurement of objects being observed; also, the crosshair, grid, or scale on such a plate”).
(n) :
(by extension) A (nearly) rectangular or square region created by a grid of horizontal and vertical lines.