Gutter snipe
One or more stamps to which is attached the full gutter from between panes, plus any amount of an adjoining stamp or stamps. This term is typically used in reference to U.S. stamps. Gutter snipes are freaks caused by misregistration of the cutting device or paper foldover.
I have a mint sheet of The Signing of The Declaration of Independence (50 stamps at 13 cents each). There is a partial stamp that runs down the side. What would be the value of this sheet?