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 pa·rab·o·la /pəˈræbələ/
 拋物線

 parabola
 拋物線

 Pa·rab·o·la n.; pl. Parabolas   Geom. (a) A kind of curve; one of the conic sections formed by the intersection of the surface of a cone with a plane parallel to one of its sides.  It is a curve, any point of which is equally distant from a fixed point, called the focus, and a fixed straight line, called the directrix.  See Focus. (b) One of a group of curves defined by the equation y = axn where n is a positive whole number or a positive fraction.  For the cubical parabola n = 3; for the semicubical parabola n = See under Cubical, and Semicubical.  The parabolas have infinite branches, but no rectilineal asymptotes.
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 parabola
      n : a plane curve formed by the intersection of a right circular
          cone and a plane parallel to an element of the curve