Legacy Codebase
Noun · Hacker Culture
Definitions
An existing codebase that has been around long enough to accumulate business-critical behavior, outdated assumptions, undocumented edge cases, and maintenance constraints. The phrase often signals that changing it safely requires caution and historical context.
In plain English: An older important codebase that is hard to change because of accumulated complexity.
Example: "The legacy codebase looks messy, but it encodes ten years of customer-specific logic."