In arrear is a phrase that means overdue, late, unpaid, behind, or in default. These synonyms can be used to describe bills, payments, or debts that are not paid on time or past due. When someone is in arrear, it can lead to financial difficulties and stress. It's important to stay current with bills and payments to avoid falling behind. Other synonyms for in arrear include deficient, delinquent, in debt, outstanding, in default, and tardy. Being aware of these synonyms can help in communication and understanding the seriousness of being in arrear.