二次曲 èrcìqū quadratic curve Origin Definitions Defs Strokes Stroke Words Sentences Sents 二次曲线 èrcìqūxiàn quadratic curve a curve of the second degree in geometry, including the circle, ellipse, hyperbola, and parabola; conic section二次曲面 èrcìqūmiàn quadric surface a surface formed by a quadratic equation in three variables, such as a sphere, ellipsoid, or paraboloid; conicoid