平面几何 píngmiànjǐhé plane geometry Origin Definitions Defs Strokes Stroke Words Sentences Sents 平面 píngmiàn noun plane (geometry) a flat surface; in mathematics, a surface containing all the straight lines that connect any two points on it几何 幾何 jǐhé geometry geometry; often used as a short form for 几何学 jǐhéxué