There are multiple definitions - click on the translation that matches your context.

stadfestelse

substantiv

full

affirmance

Definitions of affirmance

English

a statement that something is true, correct or certain

Receipt of any rent or any other act in apparent affirmance of the tenancy shall not operate as a waiver of the right to terminate this Lease.

English

when an appellate court confirms that the decision taken by a lower court was correct

The Parties agree not to appeal the affirmance.