Learner's definition of EXPENSE
1 [noncount] : the amount of money that is needed to pay for or buy something — often used after at
◊ If you spare no expense, you spend as much money as you need to in order to make something as good as possible.
These items were imported at great/considerable/enormous expense. [=it cost a lot to import them]
We were able to fix the problem at very little expense. [=for very little money]
The repairs were made at no expense to us. [=without costing us anything]
— see also at someone's expense (below)
2 [count] : an amount of money that must be spent especially regularly to pay for something — usually plural
Their expenses [=expenditures] were getting far ahead of their income.
We need to find a way to control expenses.
cutting back on expenses
legal/medical/household expenses [=costs]
I'm concerned about the project's hidden expenses.
You'll have to pay your own travel/traveling expenses.
an all-expenses paid trip [=a journey for which all costs are already paid]
3 [count] : something on which money is spent
at someone's expense
1 : paid for by someone
a fancy dinner at my parents' expense
a stadium built at the taxpayers' expense = a stadium built at taxpayer expense [=with money from taxes]
The tour is free, but all meals are at your own expense. [=you must pay for your meals]
◊ If someone makes a joke about you or laughs at you, the joke or laughter is said to be at your expense.
at the expense of
: in a way that harms (something or someone)
Malls flourished at the expense of small stores downtown.
She acquired power at the expense of friendships.
He argues that the tax cut will benefit the rich at the expense of the poor.
go to (the) expense
: to spend money on something