Continental

n.
  1. (Amer. Hist.) A soldier in the Continental army. See Continental, a., 3.
  2. (Amer. Hist.) a piece of the Continental currency, paper money issued under authority of the Continental Congress. See Continental, a., 3.

"Not worth a continental." was said of Continental currency after the American revolution, when it was considered almost worthless. Eventually, under Alexander Hamilton's direction at the Treasury department, the currency was all redeemed at full value.