Dictionary.net

An agreement made by a couple before marriage that controls certain aspects of their relationship, usually the management and ownership of property, and sometimes whether alimony will be paid if the couple later divorces. Courts usually honor premarital agreements unless one person shows that the agreement was likely to promote divorce, was written with the intention of divorcing or was entered into unfairly. A premarital agreement may also be known as a "prenuptial agreement."

an agreement that is made between a couple before marriage with provisions for property disposal should they separate or divorce.