"Sprint" is a horrible term for an iteration, even if you argue that "it's just a metaphor". The metaphors we use help shape our thinking, and creating the notion that one can "sprint, sprint, sprint, sprint" with no end, and with no rest, is silly and harmful.

That said, we don't need to coin the term "relay". Just use "iteration". No need to over-complicate things.

A huge problem in organizations I've worked with is the dehumanization of software development into a speed/efficiency equation. This drives me nuts because sometimes tools like our own (Jira) are used in ways that just don't respect the value of exploration, iteration, hypothesis testing, and evolution that makes great products. "Just Ship It" is a disease, not a rally cry. That brings me to words. Do words like sprint matter?