The word "primarily" means mainly or for the most part. It indicates that something is the most important or central focus among other things or factors. When you say something happens primarily, you are emphasizing that it occurs chiefly or predominantly in that way.
The word "primarily" comes from the Latin word "primarius," which means "of the first rank" or "principal." This Latin term is derived from "primus," meaning "first." The word evolved through Middle English before taking its current form.