Load-bearing Code

The term 'load-bearing code' can be used to refer to software that exhibits the following attributes.

• Has no documentation or automated tests
• Written by an ex-developer
• Used by a large portion of the code base
• Supports critical system processes

Jerry, these are load-bearing walls, they're not gonna come down!

Cosmo Kramer in the Seinfeld episode "The Chicken Roaster"

I have encountered load-bearing code in legacy open source applications, inherited projects, or debugging production software.