Common:
* Buck: This is the most common slang term for a dollar.
* Dollar bill: A straightforward and widely understood term.
* Single: This term refers to a single dollar bill.
* Greenback: This term refers to the color of the US dollar bill.
Less common:
* George Washington: Refers to the portrait of George Washington on the bill.
* Abraham Lincoln: Refers to the portrait of Abraham Lincoln on the bill, although this is usually reserved for the five-dollar bill.
* Fin: This term is less common, but can be used.
* Sawbuck: This term is usually used for a ten-dollar bill, but can be used for a dollar bill as well.
The best slang term to use depends on the context and who you are talking to. Some terms are more informal or regional than others.