HYPERBOLA
hyperbola
(noun) an open curve formed by a plane that cuts the base of a right circular cone
Source: WordNet® 3.1
Etymology
Noun
hyperbola (plural hyperbolas or hyperbolae or hyperbolæ)
(geometry) A conic section formed by the intersection of a cone with a plane that intersects the base of the cone and is not tangent to the cone.
Usage notes
Source: Wiktionary
Hy*per"bo*la, n. Etym: [Gr. i. e., of the angle which the cutting
plane makes with the base. See Hyperbole.] (Geom.)
Definition: A curve formed by a section of a cone, when the cutting plane
makes a greater angle with the base than the side of the cone makes.
It is a plane curve such that the difference of the distances from
any point of it to two fixed points, called foci, is equal to a given
distance. See Focus. If the cutting plane be produced so as to cut
the opposite cone, another curve will be formed, which is also an
hyperbola. Both curves are regarded as branches of the same
hyperbola. See Illust. of Conic section, and Focus.
Source: Webster’s Unabridged Dictionary 1913 Edition