If you have data in one table that should be in another table, what is their relationship called?
The relationship is called Healthy, yet dysfunctional.
If you want to know the 'term' for it:
De-Normalized.
I say it's 'healthy' because there are times that developers want performance over sanity. But just like any relationship, try not to make it the norm.
Edit: Yes, I stuck a double entendre about relationships in there. It's Friday, I'm feeling frisky.
Unnormalized Junk?
Unnormalized is a database that has never been normalized
Denormalized is a database that has been normalized at one time but someone has decided to shuffle some data around for a reason (could be performance)
Don't make the mistake of assuming that de-normalization = performance. It doesn't.
I think the OP may have worded his question ambiguously and is really trying to ask, "What do you call the relationship in which an entry in one table references a row in another table?" That is a foreign key constraint.