The word sigil comes from the Latin word “Sigillum” which was defined as a seal, or signet. It also may have been connected to the Hebrew word סגולה (segula) meaing charm, or tailsman. The way that I would define a sigil in a magickal sense of the word is a symbol that represents an intent, construct, or entity. They are uniquely created symbols that are charged with energy, while being sent into your subconscious to work in the background. This imprint in your subconscious pushes you magickally toward your desire, and the energy that the sigil was charged with is released out into the universe to manifest it. This is a very creative, and practical art that has been used, learned, and interacted with by many different people, and practitioners. They have all managed to take it into their practice, and use it in their own special ways improving the understanding, and the concept of the sigil with every iteration.