secret funds; confidential expenses
Refers to money allocated for confidential or discretionary purposes, often in government, corporate, or organizational budgets. The usage implies funds not subject to detailed public disclosure.
The use of the government's secret funds became an issue.
A large amount of confidential expenses is budgeted for that department.
Compound of 機密 (confidential, secret) and 費 (expenses, costs). The term is a straightforward Sino-Japanese compound with no irregular historical derivation.