Obligor

n. guarantor; person who receives an obligation (Law); person who is obligated

An assignment is a term used with similar meanings in the law of contracts and in the law of real estate. In both instances, it encompasses the transfer of rights held by one party - the assignor - to another party - the assignee. The legal nature of the assignment determines some additional rights and liabilities that accompany the act.
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(n.)
The person who binds himself, or gives his bond to another.
  

A person who has an obligation to pay off a debt.

A person who is contractually or legally, committed or obliged, to providing something to another person (the obligee). - (read more on Obligor)