The term ingestion refers to the process of taking code from one project and incorporating it into another project.
This PR ingests the .NET Framework 4.8 reference assemblies and other collateral into the Windows build.
Here is a public citation:
This update includes the final C++/WinRT project structure in preparation for OS ingestion for an upcoming Windows SDK (and the OS build itself).
Ingestion takes many forms. It could be a source code drop. It could be a binary drop of a foreign checked-in binary. It could be upgrading the toolchain (ingesting a new compiler). It could be changing the NuGet references. It could be upgrading the Windows SDK. For hosted services or embedded systems, it could be upgrading the operating system.
The term ingestion is used from the point of view of the project receiving the new code. The receiving project ingests the donor project. On occasion, a donor project may refer to the act of delivering code to a recipient as reverse ingestion, but I have never heard it referred to as egestion, thank goodness.