Depending on the state where the nisi order was filed, it generally is a "dismissal for failure to act on default
". For example, where an action has remained on the docket for eight months without an answer or defensive motion having been filed by any defendant, the Clerk-Magistrate shall enter an Order Nisi for Dismissal advising the plaintiff that a Judgment of Dismissal will be entered 30 days from the date of the Order unless the plaintiff either (1) requests entry of default and moves for default judgment in accordance with state statute, or (2) reports in writing that the case is active and requests that it not be dismissed.
It is also a term used in divorces where there is a waiting period from the time of separation to before the divorce becomes final.
https://www.inmateaid.com/ask-the-inmate/what-is-nisi-order#answer
Accepted Answer Date Created: February 01,2016