Greenback
Black's Law Dictionary · Henry Campbell Black, M.A. · 1910
Black's Law Dictionary
The popular and almost exclusive name applied to all United States treasury issues. It is not applied to any other species of paper currency; and, when employed in testimony by way of description, is as certain as the phrase "treasury notes."
Hickey v. Sinte, 23 Ind. 23. And see U. S. v. Howell (D. Ct) 64 Fed. 114; Spencer v. Prindle, 28 Cal. 276; Levy v. State, 79 Ala. 261.