ex|pense [ ık`spens ] noun ***
1. ) count an amount of money you spend in order to buy or do something:
Rent is our biggest expense.
You can claim part of your telephone bill as a business expense.
traveling/medical/legal expenses
a factory's operating expenses
incur an expense: The insurance will cover all expenses incurred during your time in the hospital.
cover/meet an expense: people struggling to meet their basic living expenses
a ) all expenses paid if you do something all expenses paid, someone else pays for everything:
You could win an all expenses paid trip to Barbados.
2. ) uncount the high cost of something:
A powerful computer is worth the expense if you use it regularly.
expense of: the expense and inconvenience of recovering cargo from sunken ships
go to great/considerable etc. expense (=spend a lot of money): His parents went to great trouble and expense to make sure the party was a success.
go to the expense of doing something (=spend money on doing something): We didn't want to go to the expense of sending a courier.
3. ) expenses plural money you spend as part of your job that your employer later gives back to you:
The company pays all our expenses.
put something on expenses (=charge it to your employer): Let me pay I can put it on expenses.
plus expenses: Your salary will be $70,000 a year, plus expenses.
reimburse expenses: All reasonable expenses will be reimbursed.
at someone's expense
1. ) used for saying who pays for something:
We were supposed to provide safety equipment at our own expense.
2. ) if someone has a joke or enjoys themselves at your expense, they enjoy laughing at you:
My family and friends all had a lot of fun at my expense.
at the expense of something
if one thing exists or happens at the expense of another, the second thing suffers or is not done well because of the first:
Military strength is often achieved at the expense of a country's economic health.
at great/vast/considerable expense
spending a lot of money:
At vast expense, he flew the entire family to Argentina.
=> SPARE 2

Usage of the words and phrases in modern English. 2013.