lem·nis·cate /lɛmˈnɪskət/
  雙紐線
  Lem·nis·ca·ta Lem·nis·cate n.  Geom. A curve in the form of the figure 8, with both parts symmetrical, generated by the point in which a tangent to an equilateral hyperbola meets the perpendicular on it drawn from the center.
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