The story
Its essential role was discovered in 1882 by the German mathematician Moritz Pasch.
Etymology from Wiktionary, CC BY-SA 4.0.
Pasch's axiom
Today it means: A statement in plane geometry, used implicitly by Euclid, which cannot be derived from Euclid's postulates. It states that, if a line, not passing through any vertex of a triangle, meets one side of the triangle then it meets another side. Full definition →