Arrear

1. n. That which is behind in payment, or which remains unpaid, though due; esp. a remainder, or balance which remains due when some part has been paid; arrearage; — commonly used in the plural, as, arrears of rent, wages, or taxes.
2. adv. To or in the rear; behind; backwards.

The word meanings were obtained from OPTED(The Online Plain Text English Dictionary), which is based on “The Project Gutenberg Etext of Webster’s Unabridged Dictionary” which is in turn based on the 1913 US Webster’s Unabridged Dictionary (See Project Gutenburg), as a text file.