parabola

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A plane curve formed by the intersection of a right circular cone and a plane parallel to an element of the cone or by the locus of points equidistant from a fixed line and a fixed point not on the line.

from The Century Dictionary.

• noun Same as parabole.
• noun A curve commonly defined as the intersection of a cone with a Plane parallel with its side.
• noun By extension, any algebraical curve, or branch of a curve, having the line at infinity as a real tangent.

from the GNU version of the Collaborative International Dictionary of English.

• noun 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.
• noun 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 = 3/2. See under cubical, and semicubical. The parabolas have infinite branches, but no rectilineal asymptotes.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun geometry The conic section formed by the intersection of a cone with a plane parallel to a tangent plane to the cone; the locus of points equidistant from a fixed point (the focus) and line (the directrix).
• noun rhetoric The explicit drawing of a parallel between two essentially dissimilar things, especially with a moral or didactic purpose. A parable.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a plane curve formed by the intersection of a right circular cone and a plane parallel to an element of the curve