Code Fossil
Noun · Slang & Abbreviations
Definitions
A very old piece of code preserved in place long after its original context has faded. In engineering slang, a code fossil is interesting historically and dangerous operationally because nobody is fully sure why it still exists.
In plain English: An ancient leftover piece of code still preserved in the system.
Example: "They found a code fossil from the SOAP integration era still influencing request validation in the modern REST path."