- a fourth part of the circumference of a circle; an arc of 90°
- a quarter section of a circle
- any piece or part shaped like a quarter section of a circle
- an instrument similar to the sextant in design and function, and superseded by it
- Geom. any of the four parts formed by rectangular coordinate axes on a plane surface

Origin of quadrant

Middle English from Classical Latin*quadrans,*fourth part from

*quadrare:*see quadrate