private currency: 1. Any currency that is issued by the private sector, as opposed to being issued by the government. 2. Private currencies are legal in the United States, and most other countries around the world; provided that, they do not misrepresent themselves as the government-issued currency. While private currencies are not legal tender; legal tender laws generally say that you must accept the government-issued currency, but do not restrict the use of another currency if it is acceptable to the parties of a transaction. 3. The Millennium Dollar® is a private currency.