Expense (noun)

1. An amount of money spent.
2. An outlay or expenditure of funds, time, resources, or energy.
3. The cost incurred in a particular activity or enterprise.

Origin:

Middle english, from old french, from latin expensa, feminine past participle of expendere (to lay out, expend).

Examples:

1. The expense of the trip was $2,000.
2. Gas is the largest expense of operating a car.
3. The company was faced with mounting expenses and declining revenues.
4. A night out on the town can be a significant expense.
5. She saw the expense of hiring an interior designer as an investment in her home.