First of all, I really appreciate your reply, and I'm so sorry for my delay. The word that I asked you about it mentioned in the last sentence in this paragraph.
You can compare a Mind Map to a map of a city. The center of your mind Map is like the center of the city. It represents your most important idea. The main roads leading from the center represent the main thoughts in your thinking process; the secondary roads represent your secondary thoughts, and so on. Special images or shapes can represent sites of interest or particularly interesting ideas.