n.1 cost incurred; payment of money.
2 (usu. in pl.) a costs incurred in doing a particular job etc. (will pay your expenses). b an amount paid to reimburse this (offered me {pound}40 per day expenses).
3 a thing that is a cause of much expense (the house is a real expense to run).
Phrases and idioms:
at the expense of so as to cause loss or damage or discredit to. expense account a list of an employee's expenses payable by the employer.
Etymology: ME f. AF, alt. of OF espense f. LL expensa (money) spent, past part. of L expendere EXPEND