Parabolas

Parabola Pa*rab"o*la, n.; pl. {Parabolas}. [NL., fr. Gr. ?; -- so called because its axis is parallel to the side of the cone. See {Parable}, and cf. {Parabole}.] (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 = ax^{n} where n is a positive whole number or a positive fraction. For the {cubical parabola} n = 3; for the {semicubical parabola} n = 3/2. See under {Cubical}, and {Semicubical}. The parabolas have infinite branches, but no rectilineal asymptotes. [1913 Webster]