Eating Your Own Tail

Definitions

A situation where a system or process ends up consuming its own output as input in a destructive feedback loop. Also called an ouroboros pattern.
In plain English: When a system accidentally feeds its own output back in as input, creating a destructive loop — like a snake eating itself.
Also called infinite regress in software: a build system that requires itself to build, a migration script that depends on the thing being migrated, or a monitoring system that can't alert when the alerting system is down.
Example: 'Our monitoring dashboard is hosted on the same cluster it monitors. When the cluster goes down, we lose both the services AND the ability to see that they're down.'
Source: infinite regress

c. 1600 BCE: The ouroboros — a serpent eating its own tail — appears in ancient Egyptian iconography as a symbol of cyclicality
1990s: Programmers adopt the imagery for infinite loops and self-referential bugs that consume resources until a system crashes
2000s: In startup culture, it describes a company spending more to acquire customers than those customers generate