Truncation is the act of shortening something by cutting off part of it. It can also refer to the state of being shortened. To truncate means to reduce the length of something by removing a portion of it. The act of truncation involves cutting or chopping off a part of something.
The verb to truncate means to cut or shorten. You can use an electric saw, a chainsaw, or even a karate kick to truncate a board that is too long.