n. An item that is in arrears, as periodic payments on a debt or for taxes.
the GNU version of the Collaborative International Dictionary of English
n. That which remains unpaid and overdue, after payment of a part; arrears.
The Century Dictionary and Cyclopedia
n. The state or condition of being behindhand or in arrears.
n. Arrears; amount or amounts outstanding or overdue; any sum of money remaining unpaid after previous payment of a part.
Word Usage
"In other words, if you file Chapter 13 because you are three payments delinquent, your missed payments (the mortgage "arrearage") will be paid in your plan."