Transcendental describes anything that has to do with the spiritual, non-physical world. You could describe the time you spend in the woods hiking as a physical and a transcendental experience.
When something is transcendental, it's beyond ordinary, everyday experience. It might be religious, spiritual, or otherworldly, but if it's transcendental, it transcends — or goes beyond — the regular physical realm. The adjective transcendental is used to describe a particular kind of meditation, a specific school of philosophy, and even a type of number in mathematics. Transcendental and transcend come from the Latin word transcendere, or climb over or beyond.