The story
After German mathematician Felix Klein.
Etymology from Wiktionary, CC BY-SA 4.0.
Klein quadric
Today it means: The lines of a 3-dimensional projective space, S, can be viewed as points of a 5-dimensional projective space, T. In that 5-space, the points that represent each line in S lie on a hyperbolic quadric, Q, known as the Klein quadric. Full definition →