a quarter of the circumference of a circle
"The surveyor marked the first quadrant of the circular track to measure its length accurately."
any of the four areas into which a plane is divided by two orthogonal coordinate axes
"When plotting the coordinates on the graph, each point falls neatly into one of the four quadrants defined by the x and y axes."
the area enclosed by two perpendicular radii of a circle
"The engineer marked the first quadrant on the blueprint to isolate where the new sensor should be installed."
a measuring instrument for measuring altitude of heavenly bodies
"The astronomer adjusted the brass quadrant to accurately measure the star's altitude above the horizon."
One of the four sections made by dividing an area with two perpendicular lines.
"The city planner marked the new park in the upper-left quadrant of the map to ensure it was far from the industrial zone."
The word comes from the Latin quadrāns, which meant "a fourth part" or "quarter." It entered English via Old French as a term for a quarter of something.