Nalvas -

Not a goodbye.

If you encountered this term in a scientific or medical context, "Nalvas" may be a typo for: nalvas

Elara woke at the base of the pass with frost on her eyelashes and a new weight in her chest—not grief, but something like a room with the window left open. The painted stone was gone. In her palm, instead, was a single smooth pebble with a crack running through its center, and where the crack split, a faint light glowed. Not a goodbye

It is traditionally defined as a distance of 400 cubits (roughly 200 yards or 180 meters). and where the crack split