orthochronous
Adjective
Meaning
orthochronous (not comparable)
(mathematics) Describing any Lorentz transformation or Galilean transformation which preserves the direction of time
Examples
The orthochronous, proper, proper orthochronous sets of LTs are all subgroups.
This will not always be the case; it can be shown that the composition of any two Lorentz transformations always has the positive determinant and positive inequality, a proper orthochronous transformation.