graticula

Graticula is a Latin noun meaning a small grid, lattice, or grate. In modern technical usage, the related term graticule denotes a reference network of lines that facilitates measurement, coordinate reference, or calibration. The singular Latin form graticula is mostly encountered in historical or Latin-language contexts, while graticule is the common English form.

In cartography and geodesy, the graticule refers to the network of lines of latitude and longitude drawn on a map, chart, or globe. This grid provides a coordinate reference frame and allows the estimation of distances, directions, and positions between points on the surface of the Earth or another celestial body.

In microscopy and optical instrumentation, a graticule (reticle) is a transparent plate with an etched grid or crosshair mounted in an eyepiece or inside a telescope or microscope. It is used to measure sizes, map positions, or calculate angular relationships in the field of view, typically after calibration against a known scale.

In astronomy and photogrammetry, graticules or overlays may be used on sky charts or image displays to align, calibrate, or compare features. The term can also describe grids applied to digital images to facilitate spatial analysis or scale estimation.

Etymology and usage notes: the term derives from Latin graticula, meaning a small grate or lattice. In contemporary English, graticule is the prevailing spelling, with graticula appearing mainly in Latin texts. The concept remains a foundational tool for spatial reference across disciplines.