Wiktionary
n. 1 (account receivable English) 2 (context accounting usually pluralonly English) The total monetary amount owed to a financial entity due to debts arising from sales on credit or on account.
WordNet
n. a creditor's accounts of money owed to him; normally arise from the sale of products or services
Wikipedia
Accounts receivable is a legally enforceable claim for payment held by a business against its customer/clients for goods supplied and/or services rendered in execution of the customer's order. These are generally in the form of invoices raised by a business and delivered to the customer for payment within an agreed time frame. Accounts receivable is shown in a balance sheet as an asset. It is one of a series of accounting transactions dealing with the billing of a customer for goods and services that the customer has ordered. These may be distinguished from notes receivable, which are debts created through formal legal instruments called promissory notes.