1 a quarter of a circle's circumference.
2 a plane figure enclosed by two radii of a circle at right angles and the arc cut off by them.
3 a quarter of a sphere etc.
4 a a thing, esp. a graduated strip of metal, shaped like a quarter-circle. b an instrument graduated (esp. through an arc of 90°) for taking angular measurements.
Derivatives:
quadrantal adj.
Etymology: ME f. L quadrans -antis quarter f. quattuor four
Useful english dictionary. 2012.