nisi

conj. unless (Latin)

Nisi ben Menasseh or Nisi ben Moses was a Jewish ruler of the Khazars mentioned in the Khazar Correspondence. He probably reigned in the mid to late 9th century CE. Little is known about his reign. As with other Bulanid rulers, it is unclear whether he was Khagan or Khagan Bek of the Khazars, although the latter is more likely.
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Adjective
1. not final or absolute; "the decree is nisi and not absolute"
(similar) inconclusive

(conj.)
Unless; if not.
  

This word is frequently used in legal proceedings to denote that something has been done, which is to be valid unless something else shall be done within a certain time to defeat it. For example, an order may be made that if on the day appointed to show cause, none be shown, an injunction will be dissolved of course, on motion, and production of an affidavit of service of the order. This is called an order nisi.

Under the compulsory arbitration law of Pennsylvania, on the filing of the award, judgment nisi is to be entered: which judgment is to be as valid as if it had been rendered on the verdict of a jury, unless an appeal be entered within the time required by the law.
   

This entry contains material from Bouvier's Legal Dictionary, a work published in the 1850's.