simoleon

Meaning

1. (US, slang) A dollar.
2. A fake, theoretical, or unofficial unit of currency.
3. (capitalized, sometimes, uncountable) A fake, theoretical, or unofficial unit of currency.

Etymology

Most likely a late-19th-century blend of simon (“dollar”), from simon (“sixpence coin”) (17th-century British slang, perhaps related to simony?), and Napoleon (“French gold coin worth 20 francs, bearing the image of Napoleon III”). Perhaps from New Orleans.
The gaming sense may have been chosen for its similarity to Sim.