Trihedron

A Triple of three arbitrary vectors with common vertex. The vectors are often taken to be unit vectors, and the term trihedron is perhaps most commonly encountered in the consideration of the unit Orthogonal Vectors given by ${\bf T}$, ${\bf N}$, and ${\bf B}$ (Tangent Vector, Normal Vector, and Binormal Vector).

See also Binormal Vector, Normal Vector, Tangent Vector