greenbacks

noun
  1. 1

    Any bill that is legal tender in the US (originally printed with green and black ink) issued by the Federal Reserve.

  2. 2

    The United States dollar.

  3. 3

    A unit of American currency issued during the Civil War by the Treasury Department.

Source: https://en.wiktionary.org/wiki/greenback, https://en.wiktionary.org/wiki/greenbacks