arrear

ARRE'AR, adv. [L. ad and retro.]

Behind; at the hinder part. In this sense obsolete. But from this use, we retain the word as a noun in the phrase, in arrear, to signify behind in payment.

ARRE'AR, n. That which is behind in payment, or which remains unpaid, though due. It is generally used in the plural, as the arrears of rent, wages and taxes; and supposes a part of the money already paid.