Functional currency refers to the main currency used by a business or unit of a business. It is the monetary unit of account of the principal economic environment in which an economic entity operates. International Accounting Standards (IAS) and U.S. Generally Accepted Accounting Principles (GAAP) provide rules for translation of foreign currency ...
As defined by FASB No. 52, an affiliate`s functional currency is the currency of the primary economic environment in which the affiliate generates and expends cash.
As defined by FASB No. 52, an affiliate's functional currency is the currency of the primary economic environment in which the affiliate generates and expends cash. 
The currency in which a subsidiary conducts most of its business
Money that can be used to invest in risky investments with high potential return.
The working or operating currency of a corporate affiliate, as defined by Financial Accounting Standards Board Statement No. 52