Per diem is a Latin phrase meaning 'for each day'. It is commonly used in the business world to refer to a DAILY allowance for expenses such as meals, lodging, and transportation. The term PER DIEM can be broken down into two words: DAILY (5 letters) and ADAY (4 letters). DAILY refers to something that happens or occurs every day, while ADAY is an archaic word meaning 'on a DAILY basis'. Together, these two words form the phrase PER DIEM, which is used to describe a DAILY allowance for expenses.