SIMOLEON \suh.MOW.lee.un\. n. an old US slang term for one dollar
In early eighteenth-century Britain, the small silver coin whose proper name was sixpence was often slangily called a simon. We’re not sure why, but a plausible origin lies in the name of Thomas Simon, a famous seventeenth-century engraver at the London Mint who designed some new coins after the Restoration in 1660, including the sixpence. (A New Testament reference, to St Peter “lodging with one Simon a tanner”, led to the coin later being called a tanner instead.) Simon seems to have been taken to the USA and transferred to the dollar coin (the name is said to have been recorded in the 1850s). Having in mind the much more valuable French gold coins called Napoleons, some wit bundled simon and Napoleon together and made from it simoleon.
Although the word is not used much nowadays, it is considered well known enough to appear in newspaper crossword puzzles from time to time. The crossword clues for this word have typically been things like [Clam], [Buck], or [Smacker], which follow the tradition of using slang in a clue to indicate that the answer is also slang.
Simoleon has the obscure anagram OINOMELS. Oinomel is a variant spelling of OENOMEL, pronounced \EE.nuh.mel\, which is a sweet ancient Greek beverage of wine mixed with honey.