Riemannian tensor field

From Memory Alpha, the free Star Trek reference

Riemannian tensor fields are mathematical objects belonging to the field of Riemannian geometry.

In 2366, Wesley Crusher studied a locally Euclidean metrization of a k-fold contravariant Riemannian tensor field in his free time in Ten Forward. He was interrupted by the Gatherer Brull who wasn't too keen on the subject. (TNG: "The Vengeance Factor")