Bill/bɪl/ Definition 1 of 5Pro Tip 1/3Financial Obligation The term 'bill' often indicates a sum of money you need to pay, not optional. I received a bill for the car repairs. Pro Tip 2/3Frequent Use 'Bill' is commonly used in daily life, especially for basic services and utilities. My phone bill is due every month. Pro Tip 3/3Payment Reminder A 'bill' often comes with a deadline, implying it's a reminder to pay before a certain date. The water bill must be paid by the 15th.