n. 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 90ø) for taking angular measurements. quadrantal adj.
[ ME f. L quadrans -antis quarter f. quattuor four ]