noun Usually cross hairs.
- Also called cross wire. one of the fine wires or fibers, strands of spider web, or the like, crossing in a focal plane of an optical instrument to center a target or object or to define a line of sight.
- one of the marks that aid in the positioning of overlaying images for correct registration in printing.Compare register(def 11b).
- two fine mutually perpendicular lines or wires that cross in the focal plane of a theodolite, gunsight, or other optical instrument and are used to define the line of sightAlso called: cross wires