Code Necromancy

Definitions

A humorous term for reviving, understanding, or making use of ancient, undocumented, or seemingly dead code that should not still matter but somehow does. It captures the eerie craft of working with software that has outlived its expected context.
In plain English: The strange work of bringing old or forgotten code back into understanding or use.
Example: "The migration required code necromancy because an old billing parser nobody understood was still in the critical path."