Is the Cosmos a super set of the Universe and any hypothetical multiverse(s)? I'm quite lost on the definitions of words like omniverse, megaverse, multiverse, meta-universe, universe, and cosmos. I used to think the Universe and the Cosmos were essentially the same things, but now I'm reading the latter is an orderly system (not sure what's meant by that).

Can somebody help me understand what they each represent? In 1980, Carl Sagan said "The cosmos is all that is, or ever was, or ever will be." This sounds like the Cosmos would be the greatest of all and all else would fall into that. Would it be accurate, for example, to say Cosmos > Multiverse > Universe? What about the other things I mentioned earlier?
"Cosmos" is the English cognate of the ancient Greek word which refers to the entirety of existence. It is equivalent to the Latin-derived word "universe;" the only difference between the two is the language of origin.