What does "bottom line" mean?

The ultimate result, the upshot; also, the main point or crucial factor. For example, The bottom line is that the chairman wants to dictate all of the board's decisions, or Whether or not he obeyed the law is the bottom line. This is an accounting term that refers to the earnings figures that appear on the bottom (last) line of a statement. It began to be transferred to other contexts in the mid-1900s.