弦2 xián ① [Mathematics] a (指三角形斜边) chord b (连接圆上任意两点的线段) hypotenuse ② (指月相) crescent ▸ 上弦 the first quarter of the moon ▸ 下弦 the last quarter of the moon ③ (发条) spring of a clock ▸ 给闹钟上弦 give the alarm clock a couple of winds ▸ 手表的弦断了。 The watch spring is broken. |