Buck originally refers to "buckskin" or deerskins which were used by Indians and frontiersmen as a unit of exchange in transactions with merchants.
In the saying, "The Bucks Stops Here", coined by US President Harry Truman, other sources suggest that the "buck" itself has its origins in the card game. It actually refers to the buck-horned knife that's kept in front of the dealer at some American tbales. At the start of each hand, each player puts in a number of chips (the ante) before receiving his cards. But to speed things along, in many games the person whose turn it is to deal, puts in the ante for all the players. Once the round is over, the dealer "passes the buck" and the responsibility for footing the ante moves on.
The exact history of “bucks” used for “money” is uncertain, but the leading theory, which seems likely, is that “bucks” came about as a substitute for money in the 1700s, when deerskins were a common medium of exchange for other items of value.
Many years later, when the deerskin was no longer used as a significant unit of trade, the word “buck” shifted to a more general reference to the dollar. And in many parts of the United States, “dollars” are still referred to as “bucks.”
Other term often used to refer to money:
grand
dough
lettuce
bacon
sawbuck
scratch
stash
Read more about The History of ‘Bucks’ and Other Words We Use to Mean Money featured at HuffPost.