What is the all-encompassing term that includes everything, such as planets, galaxies, and living organisms?

The term that refers to everything encompassing all matter, energy, planets, galaxies, and living organisms is "universe." The universe is the vast expanse that contains all celestial bodies as well as all forms of energy and the laws of physics that govern them.

While the word "galaxy" specifically refers to large systems made up of stars, stellar remnants, interstellar gas, dust, and dark matter, it does not encompass everything in existence. The term "multiverse" suggests the existence of multiple universes beyond our own, which is a concept in theoretical physics but does not refer to everything within our single universe. "Cosmos" can be used as a synonym for the universe, but it often emphasizes the orderly or harmonious aspects of the universe rather than serving as an all-encompassing term.

Therefore, "universe" is the most appropriate term to describe the entirety of all that exists.