The story
Named after Swiss mathematician Leonhard Euler (1707–1783), who proved the theorem in 1775.
Etymology from Wiktionary, CC BY-SA 4.0.
Euler's rotation theorem
Today it means: A theorem which states that, in 3-dimensional space, any displacement of a rigid body such that some point on it remains fixed is equivalent to a single rotation about some axis that runs through said point. Full definition →