Glossary
Also: Throttling
An upper bound on requests per period and caller, so that individual users cannot take a system down for everyone else.
Throttling protects against three things at once: accidental loops in someone else code, deliberate overload, and the cost both create.
Common approaches such as token bucket allow short bursts and only cap sustained throughput. What matters is that rejected requests answer clearly as such, including when a retry makes sense.