When you come to a conclusion, you decide that something is true after you have thought about it carefully and have considered all the relevant facts.

The conclusion of something is its ending.

The conclusion of a treaty or a business deal is the act of arranging it or agreeing it.

You can refer to something that seems certain to happen as a foregone conclusion .

You say 'in conclusion' to indicate that what you are about to say is the last thing that you want to say.

If you say that someone jumps to a conclusion, you are critical of them because they decide too quickly that something is true, when they do not know all the facts.