Definition
Plain language
A score that just tells you which way to rank options, not how far apart they really are.
As stated in the literature
In optimize-anything's cost model, a ranking-only objective: the model is required to produce a correct ordering over candidates without needing accurate absolute predictions of cost or latency.
Why it matters: Ranking-only objectives are far easier to learn than absolute prediction, and they're usually all an optimizer actually needs to make decisions.
For example, the cost model doesn't need to predict that variant A takes 12ms and variant B takes 17ms — it just needs to consistently rank A as faster than B.