Dollar: a piece of paper money worth one dollar.
No, not the Uncle, although that is in my opinion the funniest movie ever made. I'm talking about the kind of buck you tip a terrible waitress with on a $30 check. Why does the name for a male deer mean the same thing as one dollar? I'm so glad you asked!
For about 1000 years buck
has meant male deer, but you know how Americans are; we have to change everything. Flash forward to the old west, mid-19th century. Buckskins are the currency of choice among the wild men roaming the frontier. A man with a lot of skins is a wealthy one and wealthy men love to gamble. Poker was all the rage at saloons and these hunter-gamblers ate it up. Hunting and killing a deer is loads of fun, no doubt, but once you shoot the thing you need to skin it. Enter the buckskin knife.
When playing poker it is common to use a counter to keep track of who is dealing. In the old west the use of a buckskin knife as a counter became commonplace both as a counter and as a not-so-subtle reminder that cheating wasn't acceptable. When your deal is over you would literally 'pass the buck' to the next guy at the table. However, as things settled down a bit in the old west some people started to use minted silver dollars instead of buckskin knives as counters and eventually the knife fell out of use. The blade may have been gone, but the lingo that came with it lived on, so the buck
came to mean the silver dollar and, later, the regular dollar. Now, who says nothing good comes from gambling?