noun
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.
政府の機密費の使途が問題になった。
The use of the government's secret funds became an issue.
その部署には多額の機密費が計上されている。
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.