In its most general sense, a cosmos is an orderly or harmonious system. It originates from an ancient Greek term meaning “ordered world” and is the antithetical concept of chaos. Today the word is generally used as a synonym of the word Universe when considered in its orderly aspect.
In philosophy Pythagoras is said to have been the first philosopher to apply the term cosmos to the Universe, perhaps from application to the starry firmament.
In theology, the term can be used to denote the created Universe, not including the creator. In Christian theology, the word was also used to refer to ‘worldly life’ or ‘this world’ as opposed to the afterlife.