tetragon

1. Give me an old-fashioned tetragon on a central pivot every time.
   每次都给我看一个建在中轴上的四角大楼吧。
2. Calculation of Frequency of Arbitrary, Tetragon Plate with Method of Weighted Residuals
   任意四边形薄板自然频率的加权残值法计算

noun

1. a four-sided polygon

   Synonym:    quadrilateralquadrangle