hyperbola

UK: /haɪˈpɜːbələ/ US: (hī pûr′bə lə)

Inflections of 'hyperbola' (n):

hyperbolas

npl

hyperbolae

npl

WordReference Random House Unabridged Dictionary of American English © 2025

hy•per•bo•la  (hī pûr′bə lə), n. [Geom.]

1. the set of points in a plane whose distances to two fixed points in the plane have a constant difference;
   a curve consisting of two distinct and similar branches, formed by the intersection of a plane with a right circular cone when the plane makes a greater angle with the base than does the generator of the cone. Equation: x²⁄ a² − y²⁄ b² = ±1. See diag. under conic section. 

• Greek hyperbolé̄ the geometrical term, literally, excess. See hyperbole
• Neo-Latin
• 1660–70

Collins Concise English Dictionary © HarperCollins Publishers::

hyperbola / haɪˈpɜːbələ/ noun ( -las, -lae / -ˌliː/)

1. a conic section formed by a plane that cuts both bases of a cone; it consists of two branches asymptotic to two intersecting fixed lines and has two foci. Standard equation: x²/a² – y²/b² = 1 where 2a is the distance between the two intersections with the x-axis and b = a√(e² – 1), where e is the eccentricity

Etymology: 17th Century: from Greek huperbolē, literally: excess, extravagance, from hyper- + ballein to throw