Meaning of “expense” - Learner’s Dictionary

expense

noun us uk /ɪkˈspens/
Extra Examples
Child care is a major expense for many families.You can save yourself a lot of unnecessary stress and expense if you have your car serviced regularly.He was worried about the enormous expense involved.We had to buy a new TV which was an added expense.My plan involves no unnecessary expense.

B2 [ C, U ] the money that you spend on something:

You have to pay your own medical expenses.
He eventually found her the car she wanted, at great expense (= it cost him a lot of money).
at the expense of sth

If you do one thing at the expense of another, doing the first thing harms the second thing:

He spent a lot of time at work, at the expense of his marriage.
at sb's expense

If you do something at someone's expense, they pay for it:

We went on holiday at my father's expense.

in order to make someone look stupid:

Stop making jokes at my expense.

(Definition of “expense” from the Cambridge Learner’s Dictionary © Cambridge University Press)