I think you're describing two different situations:
what do you call data that is not yet fresh, and has never been fresh?
Garbage. When you read a value before initialization happens, you read uninitialized data. It's been left in whatever state from whatever touched it last. You can't even call this random because it can't be trusted to be random. It's value came from something outside the scope of your reasoning.
operation that fails if performed on an entity that's never been flushed to the database.
This data is out of sync. A good design has one, and only one, unambiguous source of truth for every piece of information. An efficient design often makes local, fast, copies from that source and attempts to keep them in sync with the slower, more persistent ones. You can call this caching, paging, virtualization, or whatever but when it fails you have the same idea represented as being in two different states because these two copies are out of sync. At least that's one name for it.
In the CAP theorem you'd call it partitioned. For some reason the data has not yet been flushed to the DB and now you wish to perform an operation before it is. If you allowed the operation to succeed now the result would be inconsistent with the DB. Since you say it will fail the result is a lack of availability. Those three ideas:
Consistency, Availability, and Partition tolerance give the CAP theorem its name.
What grew out of this idea was a concept of Eventual Consistency which encourages a design that expects consistency to fail on occasion but has a strategy to eventually correct it rather than rolling over and dying with an error the moment it's detected.
Which you should do is up to you. But these are the names that dance around this idea.