IANAL - but the legal term would be "non-disparagement" as one of the carrots the lawyer dangles. It's all very legal, very cool, and both side perfectly understand what it means.

Avoiding bad PR is one of the reasons most settlements have non-disparagement clauses, usually paired with a confidentiality clause that says you can't even talk about the settlement (and therefore you can't mention or imply the existence of the non-disparagement clause therein).