It’s a ray in that it’s a line with a definitive terminus (the camera) and drawn into the scene, like an arrow). By definition that’s a ray, not a line-segment (with two ends) or a line (goes on forever in each direction). It’s like when we say transform vs rotation or scaling; the context is giving you additional information.
Yes, I am being pedantic, and no not trying to be a jerk. It’s just a terminology thing… You start here and go on for a distance (potentially forever, hence the line-ish/ray part).
If it’s hardware supported, it would depend on what data-structure it’s being pushed through. Might not be something serviceable on a card.