testamentary : Idioms & Phrases

• noun a legal document from a probate court or court officer informing you of your appointment as executor of a will and empowering you to discharge those responsibilities
  

WordNet

• (Law), an instrument granted by the proper officer to an executor after probate of a will, authorizing him to act as executor.

Webster 1913

• noun a trust that is created under a will and that becomes active after the grantor dies
  

WordNet