Refers to money paid as compensation or reward, often in official or legal contexts. Compare with 報償金, which is more common for 'reward money'.
See also: 報償金
The government paid compensation to the informant.
secret funds
Used in governmental or organizational contexts for confidential expenditures, similar to 機密費. Not a general term for 'secret money'.
See also: 機密費
The ministry did not disclose the use of the secret funds.
機密費 specifically refers to confidential or secret funds, often in government or corporate settings, and is a near synonym for sense 2 of 報償費.
Compound of 報償 (compensation, reward) and 費 (expense, cost). The term is primarily used in administrative and legal contexts.