The term 'Monthly Expense' can refer to a variety of costs that are incurred on a regular basis. The crossword solutions for this term include RENT (4 letters), GAS (3 letters), and RENTAL (6 letters). RENT is typically the cost of living in a home or apartment, GAS is the cost of fuel for a vehicle, and RENTAL is the cost of renting a vehicle or other item. All three of these expenses are typically paid on a monthly basis.